If you believe, as the writer Anaïs Nin did, that life should be full of rich drama and inspired sex, then naturally you would be thrilled to board an elevator in a Manhattan apartment building in 1947 and encounter a staggeringly handsome young man. The fact that he is wearing a flamboyant, full-length coat of white leather and still sports a bashful smile only adds to his allure. And when you realize, upon introducing yourself, that the two of you are headed to the same cocktail party, it could seem that your fate is set. You are, after all, always looking for another lover.

You spend the next hours perched beside him on a small sofa at the party, as Nin’s biographer Deirdre Bair would later recount, talking and talking and never once mentioning the fact that you are 44 years old and married. He is 28, regally tall and wears his dark hair in a low pompadour. “Danger!” you will write in your diary that night. “He is probably homosexual.”

He is not homosexual. You learn this rather strenuously two days later, having invited him to dinner at the apartment you normally share with your husband. Your husband, a middle-aged banker named Hugo, is in Havana on business. The name of your new lover is Rupert Pole. He has the impression that you are divorced, and certainly there is no need to correct this. He himself is freshly divorced, a failed actor with pillowy lips and clear blue eyes, who until recently made his living singing and dancing on cruise ships. He plays the viola and studies astrology and is soon to go West, back to California, where he was born. He is good enough sexually to cause you to cancel your other assignations — there can be five in a week — to focus on him alone. You will later say he is the most potent man you’ve ever known.

And so. When he goes West, you go, too, climbing into his 1941 Ford roadster dressed all in purple. Rupert wears a Tyrolean hat and a wool scarf. He smokes a pipe as he drives. What you have told your husband — a man you feel warmly toward but who does not satisfy you in bed — is that you are road-tripping with a dear female friend.

It would be wrong to say that Rupert Pole is never angry, never jealous, that he sits passively in the roadster while you pop into the Denver post office to pick up general-delivery mail sent by the lovers and friends you left behind. You fight a little, especially after he is forced to wait as you write back. But there is something in Rupert, some glimmer of tolerance, some unquestioning abidance with how things are, that you are beginning to appreciate. When you reach the golden desert of the West, you make love outside on a sunbaked boulder.

From now on, your life goes more or less like this: Six weeks with one man, followed by six weeks with the other. On the East Coast, Hugo is wealthy enough to pay for your manicures and trips to your analyst, and together you take long vacations in Acapulco. But you tell Hugo that you yearn for the seclusion of the West, specifically for a small cabin in the scrubby mountains outside Pasadena, where you go to do your writing. He may presume that you are alone, but of course you are not: Rupert is now a forest ranger, and the cabin — a spartan affair owned by the Forest Service — is his station. Rupert ruins your manicures by making you scrub floors, haul water and mend socks, but you love him, at least in six-week stretches.

He believes you when you say you must return to New York for meetings with editors. He believes you when you invent magazine assignments — when, indeed, you invent whole magazines — that keep you on the East Coast. And when you tell him that you are unreachable, staying with a friend who has no phone, he believes that too. You go back and forth and back again. Up in the mountains, people start calling you “Mrs. Anaïs Pole.”

He begs you to marry him, but you put him off. Every day you are at Rupert’s house, you send a letter to Hugo, describing the loneliness of the writing life. When in New York, you write Rupert long missives complaining about how hard you are working as a journalist. You pen those letters from bed, as Hugo’s maid delivers breakfast on a tray. You have told so many lies now that you have to keep them written down in a notebook. You have two men who won’t stop believing you, and somehow that has made it impossible to leave either one.

Why won’t Rupert give up? You assume that his strapping body and pretty face will attract some younger woman who’ll stay full time. But Rupert seems to want only you. His life is a happy feedback loop: he works his job, spends the evenings reading Time magazine, waits for you to come home. His faith wears you down.

And so. In a dusty little town in the Arizona desert in 1955, as quietly as you can, you marry Rupert Pole. For the next 11 years you are the wife of two men, on two coasts. You liken yourself to a trapeze artist, swinging from one husband to the other. The lies have multiplied to the point that you now keep them in a file you refer to as “the lie box.” It has two sections: one labeled New York, one Los Angeles.

Rupert leaves forestry to teach middle school in Los Angeles. Hoping that you’ll stop traveling so much, he builds a house for you, with a stone fireplace, an outdoor writing table and a pool where you both swim naked. He grows a beer belly but remains ruthlessly good-looking and hungry — not just for sex but for sex with you.

Eventually, you tell him everything. Your body is weak from all the flights; the weight of the lies is making you old. Also, you are becoming famous as a writer, and you’ve got two men claiming your royalties on their tax returns. You unload the full truth on Rupert rather than Hugo, knowing that if Rupert hasn’t left you yet, he probably won’t now. You annul your marriage to Rupert and remain married to Hugo. After all these years, you owe Hugo something — a warped form of loyalty, perhaps, or at least access to your new wealth.

Rupert takes it all in without wavering, perhaps understanding that in losing the marriage, he has won something bigger. When slowly you start to die of cancer, you finally resolve to live full time in California because you are too weak, really, to do otherwise. On days you wish to speak to Hugo, Rupert picks up the phone and dials the number for you, allowing you to preserve the myth of your marriage. He gives you injections, takes you to the doctor, and when you crave release, he gently carries you into the glittering pool behind the house so that you may swim.

When you die, The Los Angeles Times obituary will remember you as the wife of Rupert Pole; The New York Times lists your widower as Hugh Guiler. But it is Rupert you’ve named as your literary executor, the guardian of 35,000 pages of your diaries, your fullest version of the truth. And it is Rupert who rents a small plane to fly over the coast near Santa Monica, finding a sparkling cove over which he sets your ashes adrift. When Hugo dies in 1985, eight years after you, Rupert honors his last wishes by scattering his ashes over the same waters. And now that Rupert is gone as well, having stayed on quietly in the house he built for you, having honored you by publishing new, less censored versions of your diaries — you would hope the same for him. You would hope that somebody flies what’s left of Rupert Pole up over that sparkling cove, over those billions of mingling sea molecules, and finds exactly the right moment to let him go.