Climbing the Stairs to Adultery : AN ADULTERY <i> by Alexander Theroux (Simon & Schuster: $17.95; 375 pp.) </i>

Do men hate women? Or do women hate men? Are men remote, incapable of intimacy, and interested only in their professional achievements? Are women fickle, selfish and interested only in security? These questions have dominated social discussion since marriage stopped being an economic or agrarian necessity and became a matter of choice, like which detergent to use or what make of car to drive. Recently, at least, majority opinion seems to be that women are the victims of masculine failings. Dozens of vacuous self-help books show women how to deal with men’s refusal to behave the way they want them to behave. Oceans of statistics increase the panic by telling women that there aren’t enough men to go around. Perhaps the least of Alexander Theroux’s accomplishments in this fascinating and eloquent book about adultery is to tell the man’s side of the story.

Christian Ford, a painter who teaches at a small New Hampshire prep school, falls in love with an enchanting woman who works at the local art gallery. She’s married, but her husband doesn’t understand her. (Sound familiar?) As the months and seasons pass, Christian and Farol begin their quirky, passionate affair. He’s withdrawn at first, and then she is. She leaves her husband and then goes back to him, and then leaves him again. Sometimes Christian goes off to his house on Cape Cod and leaves her desperately lonely for him. Sometimes he’s so desperate that he parks across from her apartment and watches the flicker of her television set through the windows.

Christian is still tied to an old love, Marina, and he goes back to her when things with Farol are too painful to bear. “Farol and Marina:” Theroux writes, “It was as if, almost geometrically designed for it, each threw the other into sharp relief. And yet while both shared the same range, the same beauty, the same sort of background, the same lack of education, they nevertheless might have been from different species. Farol wanted things; Marina couldn’t will. I sympathized with Marina.” But Christian is obsessed with Farol, and so he becomes both the betrayer, cuckolding Farol’s husband and cheating on Marina, and the betrayed when Farol changes and changes again and finally dumps him for a doctor. This thoughtful, wonderfully written book explores every aspect of this intimate marital minuet. In defining adultery, Theroux does some of his best writing. “And so I always stayed,” he writes. “The worst moment in adultery is when you are climbing the stairs. I’d go up to the top bedroom, undress in the cold dark, and then suddenly she’d be there in the bed beside me where both of us sought to rescue, as we rolled toward the other with primordial hunger, what together in a desperate act of sinister dexterity we separately were yet convinced neither of us could save. It was prohibited to care.” Later he writes of Farol and her feelings about her husband. “She felt a certain power, a justice, I think, in hurting the man who she felt so often had hurt her . . . and yet what she shared with me on those quick and timid trips, attempting to transubstantiate acrimony into ardor, was also and at the same time her way of keeping it from someone else. It was at once a theft as well as a gift. She gave away only what she stole.”

Theroux’s prose is orchestrated like a full symphony. The rich, plummy rhythms of his sentences are reminiscent of Henry James, and Farol herself is certainly a descendant of Isabel Archer’s girlish conflicts and Charlotte Stant’s delicious conniving. At times, though, Theroux is witty and disdainfully acerbic, particularly on the subject of New Hampshire and its small-town gentry. “There were a lot of preppie women full of refinements and angles who came to these things,” he writes of a local art opening. “They all used three names like Sarah Munster Townshend and Lucy Tevepaugh Knight and Marge Jackson Mixter, but were usually called ‘Cokey’ or ‘Poky’ or ‘Mopsy’ and were horribly energetic and ran boutiques and wore wraparound dresses and sunglasses on top of their heads. The expensive earrings they wore did nothing to soften their overtanned faces, which were cracked and leathery like catcher’s mitts, and all spoke with that basic preppie honk that had ripened over the years into a hoarse crow-squawk.”

I met Alexander Theroux once, on a summer afternoon in Cape Cod, and both in person and in this novel he’s an unusual mix of boyish openness and innocence (he sort of bounds around, and talks a lot), and highly educated critical intelligence. The combination gives this story its eccentric, personal twist. He’s not out to dissect Farol’s feelings. He loves her! But he can’t help himself. He’s a scholar, he’s a poet, and he’s a country boy who complains when his girl wants to go out to a fancy restaurant.

“At times she seemed almost rigid with greed,” Theroux writes of Farol near the end. “I had never quite believed her feelings were so conditioned by material interests. But as she thought she was always one man away from welfare, it became impossible for her to hide any longer her regrets about who had sacrificed what for whom.” In the end, Farol is pathetic and confused, the victim of a stony father and her own mistaken dreams. The book is never an indictment--only a description, and although Christian Ford doesn’t think much of psychiatrists, there’s a distinct Freudian component in his final understanding of Farol.

“Farol had loved other men and she’d left them,” he concludes. “But I felt I was the exception. Was it therefore wrong of me to worry that the only thing an exception can possibly prove is that the rule is faulty?” Christian Ford is so dumb, so innocent that he’s shocked and surprised when Farol says that she loves him and then changes her mind! At the same time he’s as smart as Alexander Theroux--which is very smart indeed.