Witt’s sexual quest leads her to Burning Man’s “orgy dome,” a B.D.S.M. video shoot, an orgasmic-meditation workshop. Illustration by Olimpia Zagnoli

Few places are less conducive to erotic optimism than the packed waiting room of a public health clinic in Brooklyn. Sitting on a hard plastic chair under a fluorescent buzz as an employee lectures on proper condom use—a catechism you know by heart yet sometimes fail to heed—you may conclude, as Emily Witt did, that the time has come to change your life. It was March of 2012. Just before Valentine’s Day, Witt had slept with a friend. She was single; he was not. A few weeks later, he called to report that he might have chlamydia. He was overcome with guilt. His girlfriend was enraged. Witt didn’t feel too great, either. She was thirty, and depressed after a recent breakup. Though she had spent the ensuing months hooking up with various acquaintances, her hopes were set on long-term monogamy. “I still envisioned my sexual experience eventually reaching a terminus, like a monorail gliding to a stop at Epcot Center,” Witt writes in “Future Sex” (Farrar, Straus & Giroux), her gutsy first book. Instead, she found herself enmeshed in “sexual relationships that I could not describe in language and that failed my moral ideals.” She didn’t have chlamydia, it turned out. What she caught was worse: a dismal self-accounting of her existential shortcomings.

Marriage, for many, signals the start of a new life stage. As Witt’s image of the Epcot monorail suggests, she preferred to see it as an endpoint, the moment that would bring the aimless liaisons of her single years to a full stop. Witt grew up in Minneapolis, went to college at Brown, and got a master’s degree in investigative journalism at Columbia. She was raised by liberal boomer parents who came of age in the sixties. Influenced by that decade’s liberties, and chastened by its excesses, they encouraged her to think of youthful sexual experimentation as a healthy prelude to a coupled life. In this, Witt was hardly alone. For young, straight, well-educated American women, sleeping around for pleasure and experience has become a social convention, the way dancing the cotillion at a débutante ball once was.

Witt was ready to move on. Following her visit to the clinic, she fantasized about giving herself over to “the project of wifeliness,” as she saw many of her peers doing, indulging in the sort of triumphal social-media posts—engagement photos, wedding photos, baby photos—that advertise the twenty-first-century life cycle of young couples. Monogamy, she felt, would be all the more satisfying for being obviously traditional, a path she could see as a “destiny rather than a choice.” She was tired of choosing. Better, she thought, to fall in love with one person and have sex with him for the foreseeable future.

But love failed to arrive. Her monorail glided on, Epcot nowhere in sight. Without the pressure of emotional commitment, Witt was free to do what she liked sexually, but she had little use for a freedom she had already decided to give up.

Maybe the problem had to do with a failure of imagination. Sexual freedom can be put to more interesting uses than sleeping with your friends. Those of us born in the nineteen-eighties belong to the first generation whose experience of pornography comes almost exclusively from the Internet, which, Witt points out, constitutes “the most comprehensive visual repository of sexual fantasy in human history.” Never before has such a wide variety of sexual preferences and behaviors enjoyed such social sanction, or been so easy to explore by typing a few words into a search engine in the privacy and the safety of one’s own home. Google may be the great sexual equalizer. “The answers its algorithms harvested assured each person of the presence of the like-minded: no one need be alone with her aberrant desires, and no desires were aberrant,” Witt writes. She began to see that she was living in a time of unprecedented erotic possibility, a sort of sexual future. Might she have a particular set of unrealized desires, a sexual identity she hadn’t yet discovered?

Witt decided to take action. She bought a ticket to San Francisco in order to report on the sexual subcultures she had reason to believe she would find there. (Parts of “Future Sex” first appeared in n+1, to which Witt is a frequent contributor, as well as in the London Review of Books and Matter.) “They believed in intentional communities that could successfully disrupt the monogamous heterosexual tradition,” she writes, with a touch of the East Coaster’s skepticism toward the Bay Area’s positive-thinking citizens. “They gave their choices names and they conceived of their actions as social movements.” But she is honest about her true motivations: “I used the West Coast and journalism as alibis.” She was going to see how strangers in California used the Internet to organize and make sense of their desires, but the life she intended to hack was her own.

Witt’s first stop was online dating. She used OkCupid—Tinder was months away from launching —and discovered that, though its matchmaking algorithm could be eerily accurate about the sorts of people she would like, it couldn’t predict whether the sight of those people in the flesh would flood her with desire or leave her cold. This is understandable. Even if you’ve been happily partnered for years, let me recommend that you fill out an OkCupid profile to see what it’s like to squeeze your personality and desires through the sieve of questions posed by its jovial anthropomorphic algorithm. How much influence do your parents have over your life? Do you think you’re smarter than most people? Which are worse, starving children or abused animals, and which answer would you accept in a prospective match? Will your sanity be intact at the end of this interrogation?

While still in New York, Witt went out with a composer, a woodworker, and a hair stylist. In San Francisco, she met a Brazilian who showed her his marijuana plants. Even when her dates exceeded what Witt calls, in self-deprecating scare quotes, her “standards,” attraction failed to materialize. “Until the bodies were introduced, seduction was only provisional,” she writes.

Witt found that she often couldn’t discuss sex with her OkCupid prospects. It struck her as too direct. In this, she was not alone. One way that companies mitigate their female customers’ sense of vulnerability, Witt learns, is through the notion of “the clean, well-lighted place.” Women are more likely to go for sex, entrepreneurs have found, if it’s not presented with a louche, porny aesthetic. When Witt was using OkCupid, she felt that “the right to avoid the subject of sex was structurally embedded” in the site. Feminist sex-toy shops long ago discovered that women prefer to buy dildos and vibrators if they are displayed like Brancusi sculptures, the kind of objet d’art that you might find on a coffee table at West Elm rather than at an XXX peepshow den in pre-Giuliani Times Square. It’s a marketing tactic meant to give women a sense of order in their lives, akin to Marie Kondo’s teachings on “decluttering.”

The cleanest, best-lighted place Witt finds is OneTaste, a San Francisco company specializing in “orgasmic meditation.” At an open house at the organization’s headquarters, a man and a woman projecting “the human neutrality of an Apple store or IKEA” lead a group of visitors in the sort of ice-breaker games that recall college orientation, mildly spiked with eros. Going around a circle, participants describe their “red hot desire”; one after another, they agree to sit in the “hot seat” and answer questions posed to them by their fellows, who are instructed to limit all responses to “thank you.” Eye contact is encouraged.