Sometimes you feel like your love affair with this city is turning into a bad marriage. It was so wonderful at first, so promising. You chose San Francisco 15 years ago on a whim, because it is a city full of people with whims. You had been traveling for a year after college, and when your money ran out you knew you had to land someplace where there was a real city with real nature nearby. You were lured by San Francisco's improbable terrain, its old-worldish charm and its history of bemused tolerance for all kinds of misfits. You figured it was a place where you could settle and still have the sense of traveling, of wandering well-known streets and always being surprised. So you drove someone's else's big Buick Riviera all the way west, and when you finally saw the Golden Gate Bridge you had a giddy sense of amazement that you had found what you were looking for. That you were finally home.

The first phase of romance ended with a series of little disappointments -- bad public transportation, crazed roommates, high rents, low pay, impossible parking. Your affection for the city became more complicated, but your struggles made you that much more loyal. Every so often -- walking in the arboretum in Golden Gate Park where the irises and poppies spread like common grass, watching a parade of ornery bicyclists -- you'd be amazed all over again at the city. You remember the day after the big earthquake in 1989, a warm blue day, when everything in the city was shut down but its beauty. Everybody was walking around outside, happy to be alive in such a splendid, sometimes terrible city. A city worth all the risks.

But in the past few years, you've watched the character of the city changing, with baby-faced Silicon Valley entrepreneurs and Lexus-driving lawyers pushing the artists, dreamers and immigrants into tighter and tighter corners. You married a delightful man who loved exploring the city as much as you do, and you saw him change, too, from a scruffy public defender who followed the Grateful Dead into a highly paid attorney who wore Italian suits, drank single-malt scotch and cheated on his wife.

The city you knew so well together stopped sparkling. After you got divorced, everything became dull. The romance left San Francisco the way the youth and attractiveness drained out of your face. You became invisible on the streets and only saw the cracked and dirty sidewalks. Walking outside your Haight-Ashbury flat, you saw more and more homeless people every day, sleeping under cardboard, using their dirty bags of possessions as pillows. You tried to avoid them, but they were too familiar, every year a little more raw. Now you sometimes wonder if it would just be better to leave.

Then one day a postcard of a silver propeller plane lands on your doorstep from the French professor you last saw in Milan for a weekend in spring. He had casually mentioned that he'd like to visit you in San Francisco sometime, and you said sure, knowing it would never happen. Now he writes in his poor English that he is "very exciting to come," and he has already bought his ticket to San Francisco, departing 12 days after he arrives. During this time, he says, he will be entirely under your responsibility. He is leaving you to decide everything for your amorous trip since you know his tastes: big, comfy beds.

You drop the postcard because it is impossible. How can you spend almost two weeks on your own turf with a man you have known for only a few days in a fantasy world of islands and antique hotels? You won't be able to sustain the romance. He will become bored with you and your mundane little world. He will sneer at your shabby flat and think the art is bad and that you have way too many shoes hidden under the bed. He'll be appalled at how often you check your messages and e-mail. He'll realize that you aren't sexy and voluptuous, you're fat. After believing for a few short days in Italy that you are a lively, amusing, well-read woman of the world, he will leave understanding that you are just another ugly American. And you will never see him again.

Not knowing what else to do, you find a postcard of a couple driving a 1950s convertible on the beach and write that you can't wait to see him, but you leave the card in your bag for days, finally remembering to drop it, dog-eared, into the mailbox. He sends back a photo of the Golden Gate Bridge disappearing into the fog and says he's very excited, more and more. You realize he really has his sights set on San Francisco. He has spent only three days in the United States in his life, in New York 15 years ago, and now you are responsible for his once-in-a-lifetime trip to California.

Well, you say to yourself, he's a lucky guy. And then you get out the maps. You come up with a plan for 10 perfect days in California, your California, and you send him a postcard promising him an island, too.

The day finally comes when the professor is supposed to arrive. You spend the whole morning taking down all the art in the house, rearranging it and then putting it back where it was in the first place. You change your clothes several times, too, and eventually just put on your worn jeans and cowboy boots because you figure he might as well know right off the bat that you are not even trying to impersonate a European intellectual or a delicate French beauty. You are a big American blond.

You wait in the international terminal as homebound passengers roll their carts toward open-armed relatives and weary honeymooners catch their first glimpse of this notoriously romantic city. Finally you see the familiar denim jacket, silver bracelet and chestnut curls. M. embraces you and you can't believe you're actually here at the airport, picking up a man you met over breakfast on an Italian island a year ago, a man you've known for a total of six days. At first you can't remember a word of Italian, and you lead him out of the maze to the parking lot in silence, hoping you will even be able to communicate with each other for 12 days. "Eleven hours," he says. "Can I smoke yet?" You tell him that California is a non-smoking state and he has a flicker of panic before he lights up.

You load his compact bag into the car, afraid to glance at him, and drive home on the industrial freeway next to big billboards and bald brown hills. He is puzzled by the ugliness and you remind him, your Italian coming back now, that the highway to the airport is ugly in Paris, too. You exit onto hilly Dolores Street, with its stately rows of palm trees and Victorian houses, and he begins to become excited. You wind up a steep back hill toward the Haight-Ashbury and as he hangs on to the corners of his seat the entire city comes into view, from the hills of houses to the toy blocks and triangles downtown. The view almost surprises you and he is entranced. Over and over he says he can't believe he's here.

You warn him that your house is bohemian as you open the gate to the 1907 apartment building where you live. He surveys the high ceilings, hardwood floors, molded wainscotting, cheerful kitchen, yard sale furniture and books everywhere and pronounces the whole place charming. He walks right into your room and hops onto your bed. "Monumentale," he says, and looks you in the eye. While you explain how you thought it was kind of important and symbolic to get a really good bed after your divorce, he starts to kiss you and it is so good to touch someone, him, again. He is much too wide awake to lie around napping, so you take him for a quick tour. You walk down grimy Haight Street, with its tattoo parlors, head shops, used clothing stores, burrito restaurants and bondage boutiques, and M. stops in front of almost every window, fascinated. You hate the Haight after all these years, but today it seems like a friendly street carnival. You recount stories about the '60s rock stars who used to live here, how there used to be old sofas in the revival movie house, and how much you like it that after all these years you know the people in the produce market, the independent bookstore, the post office and the hardware store. It's a real neighborhood. Someone near the park offers you buds and doses, sotto voce, and M. is delighted that he's on the famous hippie Haight Street and someone is actually trying to sell him drugs.

You cross over into Golden Gate Park, half as long as the city itself, a variegated jewel that never would have been built if it were up to anyone today. You wander through the tunnel, where someone ingeniously molded stalactites on the ceiling years ago, and then emerge into the grassy sun. On a nearby hill, drummers are drumming African drums, barefoot women in Indian skirts are dancing, guys in long baggy shorts are throwing frisbees and people are lying out bare-chested, catching the last rays before the chill. "This is just how I imagined San Francisco," says M., and it is how you imagined it, too, before you moved here. You walk over to the Hall of Flowers, closed since it was battered by a big storm a few years ago, and M. gasps at the beauty of the fragile Victorian glass palace surrounded by towering palm trees and tidy beds of flowers. You show him the huge square of dahlias nearby, bursting in color, and point out the rocks that someone has arranged into a miniature model of the Grand Canyon. He can't believe the park is so vast and uncrowded. You can't believe how long it's been since you've actually looked around here instead of bicycling through, unseeing, just getting exercise.

The sun sets and you walk back toward home, veering off to Cole Valley, which is near the Haight but in another, tidier, more gentrified world. M. admires how European the neighborhood is, with its cheese shop, its sleek blond-wood restaurants, its compact bars and cafes. You duck down a side street into your favorite sushi restaurant, a plain place with plastic chairs and Japanese calendars. You pick your sushi adventurously, happy to be taking a Parisian to a meal he could never get in Paris without paying a fortune. He savors every bite of fish and marvels at its freshness. The sushi chef comes over to tell you that you have such good taste that next time you're in he promises he'll feed you a really exquisite fish liver. You love that of all the many times you've been in this little restaurant the chef waits until you're with a snobbish Parisian to compliment you on your palate. You walk a few short blocks home, where M. says he already feels comfortable. He lights a cigar even though no one ever smokes in your house and watches the church lights glow in the distance.

In the morning you are confused by having someone in your bed. You bring him coffee as he wakes up, and he sips tentatively, his first American coffee, and is surprised it is so good. Of course it's good, you tell him. This is San Francisco, not America.

That day you take him along for the ride, showing him the collective writers office where you work. He climbs the stairs to the loft and takes in the punching bag, the Christmas lights, the plastic shower curtains dividing the cubicles, and says you would never find anything like this in Europe. You're anxious about introducing him to the people you work with.

It's odd to have your fantasy world meet your reality. You still worry about what people will think about this dalliance with a married Frenchman. You know it's good for you. But other friends have been surprised and disapproving. One asked you how you're any different from the woman your husband escaped your marriage with, the woman you found late one evening snuggled up with your ex on the deck in sleeping bags, drinking wine and looking at the moon. You know there is a world of difference, that you are no threat to M. and his wife, that they are complicated French people who have a clear understanding, that M. isn't going to leave her and move in with you the next week, as your ex did with his girlfriend. You aren't going to move to Paris; you won't even visit there. You don't speak French, and M. doesn't speak English. There's no risk. You keep telling yourself that.

You have lunch at a Thai restaurant with two of the women you work with, and even though they don't speak much of the same languages, M. begins to believe that all the women in San Francisco are smart and well-traveled, and like to laugh. Your friends know that M. has given you a little sparkle back. They know that it's exactly because there's no risk that you've been able, for a few days here and there, to peel away your depression, to peek outside again at all that is alive around you. They pronounce him charming and sexy, which he loves hearing repeated.

You take him over the Bay Bridge to Berkeley, where you teach a class. He scrutinizes your clothes when you get out of the car and says you look too sexy to be a professor, all the male students must want to sleep with you. You say that here in America it isn't taken for granted that teachers sleep with their students, and he shrugs: your loss. It crosses your mind that you're glad you're not married to a guy like this, and you put your hair into a tight bun before going in. He wanders around taking in the sights of the great American university he heard so much about in the '60s.

Afterwards, you drive all the way around the bay and get lost looking for the Richmond Bridge. Suddenly there are strip malls and housing developments everywhere. "We're outside the oasis," says M. You find the bridge and pass by San Quentin prison, where M. asks whether it's really true that they still execute people there. This, he says, is completely barbaric; no one in Europe understands it. You say, uneasily, that you went to the demonstrations against the first new execution in years, but now there are so many it's hard to keep track. You tell him that one in 250 Americans is in prison -- that one in five black male Californians will spend time there -- and he just shakes his head. This is the America he has heard about.

You wind your way up Mount Tamalpais, the big sleeping woman that looms over Marin County. You park at the trailhead to the secret entrance to Muir Woods, where you can descend into the tall trees without ever seeing a tourist. You walk in silence on the dark trail, taking in the prehistoric ferns and soft needles under your feet. Finally you tell M. that you're worried that after 12 days he'll get tired of you. Maybe, he says, but after 12 days you might get tired of me, too. He takes your hand and tells you you're a sweet woman, you're so easy to be with. You tell him he is welcome to his space whenever he needs it, trying to say that in Italian. He nods soberly, agreeing, and then tries to suppress a laugh. You don't understand what's so funny and he explains that he can't help it, it's just too much, a Californian talking about having space like that. You tell him to visualize himself abandoned on a California trail and he grabs on tightly to your arm, and then your waist.

You keep descending until you reach the redwoods and then a creek far below. Light bursts in between great soft branches and dapples the forest floor. You take the path that winds around huge tree stumps and cathedral circles of redwoods. "Incredible," M. says, staring up. There is nothing like this in Europe. It is amazing that such a magical place is so close to your home, and you rarely visit. You hike back to the top of the trail, check into the cozy Mountain Home Inn there and have a drink on the terrace, watching San Francisco peek between the distant hills like the Emerald City. "Wonderful," says M. "Gorgeous." You remember another terrace overlooking the Mediterranean with him and feel the same sense of luxuriating in a perfect moment. The next morning you drive down the curving road to Stinson Beach. This is the first time M. has seen the Pacific Ocean. It may be called pacific, he says, but it doesn't seem peaceful at all compared with the Mediterranean. And so cold! You walk barefoot in the sand until you find a cluster of rocks that you can climb on and stretch out in the morning sun, watching the waves crash. He searches around to see if there is anyone watching, if you could get away with making love on the beach. The idea tickles you and then you flash on a time your ex wanted to make love on the beach, so full of desire, so dead now, and you wonder whether you can ever feel free and sexy at home without feeling haunted. The place is too full of memories, all spoiled.

Eventually you make your way back to San Francisco along the rugged coast. M. says it looks like Spain. "How can it be so wild so near the city?" he asks, and you wonder the same thing, silently toasting whoever had the foresight years ago to leave the headlands near San Francisco undeveloped. You drive over the Golden Gate Bridge, its orange girders bright against the blue sky, and on this miraculously clear morning you can see from Mount Diablo in the east to the sailboats in the bay to the tidy stripes of streets climbing the sides of San Francisco to the Farallon islands out in the ocean. You make your way across and into the Marina District, where you point out the Palace of Fine Arts, a building you love because it is encircled by huge statues of terra-cotta women who are facing butt-out to the world, making fun of the whole business of imposing city monuments. You head across the city and do what you've never done, drive down Lombard Street, the crookedest street in the world, and when M. is surprised at the zig-zag, you shrug your shoulders like it's just another normal street in San Francisco.

You arrive in North Beach, and from the top of the parking garage M. surveys the city and its Victorian houses. "It's a doll's city!" he says. "It isn't real." You walk to your favorite Italian cafe and have an espresso, watching the passersby. You love speaking Italian in North Beach, which is full of Italians, without seeming like you're trying too hard. Spending time in your city speaking another language makes it all new.

M. announces, with his new vocabulary, that he wants to "take his space" and is going to explore the city by himself for a while. It makes you nervous to abandon him, but you realize he has traveled the world by himself and will be able to figure out how to get to the Museum of Modern Art by 4 p.m.

When you see him again, he has the city all figured out. He has discovered Chinatown and says the Financial District has no charm and the shop windows are boring to look at. He strides through the art museum, making his snap art professor judgments: The early Calder works are interesting, that Matisse is beautiful, Clyfford Still is no big deal, he isn't so sure about the California hyper-realism. He pauses at a glass cube and explains that he can lecture for three hours about this glass cube. You ask what he can possibly say and he becomes animated. This chair! he exclaims, pointing to a clean, simple metal-and-leather seat in the middle of the room. This chair would not have been possible without this cube. He goes on and on about an object just being what it is, what you see, positive and negative spaces, and you, amused at his performance, pull him along to the Rothko, where you have common ground standing there in front of the deep, vibrating, infinite red.

You take him home for dinner, and do the thing you have missed most since you were divorced, which is to cook for a man as a prelude to sleeping with him. You tantalize all his senses with a meal: fresh mozzarella and summer tomatoes with basil; orecchiete pasta with cauliflower, toasted pine nuts, currants soaked in white wine and reggiano cheese; good crusty California bread; salad greens with olive oil, shallots and lemon. He abandons himself to the meal and the wine and can't help himself, he has another serving. You bring him espresso and an alambic brandy made in Ukiah that you think is better than most cognac, and he agrees. He smokes a cigar and you smoke one of the Gitanes cigarettes he sent you last year for Christmas and then, completely satisfied, you make yourselves dessert.

For the next two days, you say you are out of town and play San Francisco tourist. You take M. to Fisherman's Wharf to catch a ferry, and are amused to see the professor of the philosophy of aesthetics pawing through a bin in a cheesy souvenir shop looking for T-shirts to bring home to his kids. You promise him you'll come up with something better than a baseball cap that says Alcatraz. You wait for the ferry and watch the crowd of sea lions sunning themselves on the pier. On the ferry, you feel like it's the boat to Ischia, a romantic voyage, even if you're only going to Tiburon to eat lunch. You have a big Mexican lunch with all of San Francisco and Angel Island before you, and you take the ferry back to the city again, a little tipsy, stretched out on the deck kissing, and then you head toward North Beach.

You climb up to a friend's apartment on the Filbert Steps, a steep garden staircase with quirky wooden houses perched on the sides, where you watch the sky turn pink with the Bay Bridge in the background. Suddenly a flock of bright green parrots flies into view and it is just another little daily San Francisco miracle. Then you drag him to the top of Coit Tower, and you realize you never go to Coit Tower to see the sunset. You tell him the story of Lily Coit, who built the big phallic firehose as a monument to firemen, whom she liked very much. It's a glorious, rare day, and you take in all the territory from the hills of North Beach to Mount Tam and Tiburon. You can't believe this is your backyard. "This," says M., "is too pretty."

You take him to a swanky bar in North Beach to watch people, checking out whether the couples fit together, deciding if you like their clothes and commenting on them all in Italian. Then you cross the street to eat at one of your favorite restaurants, a tiny, unpretentious trattoria where the food tastes like Tuscany and there are no tourists. You take him to City Lights bookstore, talk about the beatniks and have a late drink at Vesuvio's bar. You are visiting all the places you used to love to wander with your ex on a Sunday afternoon, reclaiming territory you have avoided, happy the romance of North Beach outlived your relationship.

The next morning, you take M. to the Castro, the city's gay district, rainbow flag fluttering at the portal. He is fascinated by the men casually walking around in couples. The Castro, you tell him, isn't as lively as it was in the early '80s, before AIDS made it a kind of living ghost town. But it is becoming brighter again. You show him the magnificent gilded Castro Theatre, where the organist rises to play music before the film, always ending with "San Francisco, Open Your Golden Gate" as it descends, the entire audience singing and clapping and whooping it up. Walking around outside, he says that one of the biggest tragedies of his life would be if one of his sons turned out to be gay. How can this sophisticated man say something like that? You ask if he has gay friends, and he says sure. Wouldn't you just want your son to be happy? you ask. Sure, he says, but how can you be happy if you don't love women? What we have here, you say, is a cultural difference.

After that, you take him to the dungeon of the gay leather shop, with its displays of whips, chains and foot-long dildoes. He asks if you take all your tourists here, and you tell him only the ones who have been bad. He promises to make no more anti-gay remarks if you just take him out of the dungeon. So you climb the stairs and he nonchalantly fingers a couple of leather jackets and flirts a little with the shopkeeper. Then you take him to a wonderful little seafood restaurant on Castro with a diner atmosphere and he comments about how nice it is that people mix so well in San Francisco before he tucks into his crab.

That afternoon, you have a few of your friends over to meet M. Drinking wine in your garden, he is impressed by how Americans are not all like what he has expected. M. compliments one of your friends, a journalist in his 60s, for speaking French perfectly, with no trace of an accent. He says that your Italian-speaking graphic designer friend, a fine-boned 50-year-old with a strong sense of style, is the type of woman who would be at home in any great city in the world. He's only a little confused by an artist friend who wears vintage housedresses; you have to explain that she isn't really like a Midwestern woman from the 1940s, that she wears those clothes a little ironically.

You are surprised, there in your garden, to find yourself happy. If M. lived in San Francisco, if there were any possibility that he could break your heart, you never would have allowed yourself the pleasure of him for fear of the pain. You know he'll be leaving in a week, but that still seems far enough away not to anticipate the sadness. For this moment, you're completely content. M. has not only allowed you to open your heart a crack, he has made you open your eyes and fall back in love with your city.

When the light dims, your friend Elena leaves, tossing you a set of keys. M. asks what those are for, and you tell him, the convertible. You can't go to Southern California without a convertible, can you?