All the sex women want, at the touch of a button: ‘Future Sex’ explores being single now.

Fifteen years ago, I was a young music critic spending time in New York, discovering that a number of men in the industry wanted to have sex with me. I figured this out because they said things like “I want to have sex with you,” and offered up hotel rooms. (Now they’d probably save themselves the trouble, and just swipe right.)

I quickly understood this onslaught of attention had little to do with me. I was just there, in the green room, at the listening party, in the studio, in the club. My presence in these charged male arenas shone a great, wide spotlight of desire in my direction. Sometimes it was flattering. Mostly it was not. It didn’t mean anything.

The music industry presented as a sexual free-for-all, a raucous, around-the-clock global party where all the old rules weren’t supposed to apply.

Except that the old rules still did apply. At least to me, as a young woman. I was constantly aware that a single misstep could jeopardize my career, livelihood, reputation, romantic options. And I wasn’t interested in random hotel sex anyway. I wanted someone with whom to share inside jokes, and milestones and meals. I wasn’t finding it.

In the years since, this experience has migrated online — and become strikingly common. In the Tinder era, it’s a given that offers for casual sex abound and relationships prove elusive.

Emily Witt’s whip-smart new book “Future Sex” tackles this trend, with clarity and courage.

“Future Sex” belongs to a spate of recent books about single women — who now outnumber married women for the first time in U.S. history — including Rebecca Traister’s “All the Single Ladies” and Kate Bolick’s “Spinster.” Sex and dating have become a hot topic among female intellectuals.

As a result, certain things are now widely discussed: the erosion of gender roles, the proliferation of porn, the depersonalized nature of online dating, widespread loneliness.

What’s rarely broached is what this all means for actual sex — for whom we choose to sleep with, and under what circumstances — and how we think and talk about that.

Witt sees this as one of the pressing questions of our age. How do we envision a female sexuality unhooked (albeit reluctantly) from the endgame of monogamous marriage?

In “Future Sex,” she plays this out.

The story begins in a familiar way: Witt is 30, straight, single and childless. Though she dates frequently, and enjoys encounters with male friends, she expects monogamous marriage — “an eschatological event, messianic in its totality” — to one day arrive.

But it fails to materialize. And so Witt joins the ranks of women across America who wonder “what had happened to the adult life they had imagined as children, and whether to blame its elusiveness on material changes or personal shortcomings.”

The tech-driven, 21st century sexual realm they inhabit instead is endlessly confusing, the men “listless dilettantes, the women gym-toned and frantically successful.” Here, the old strategies (withholding sex until an emotional bond is formed) fall flat. New ones (sex sans commitment) risk health, safety and social judgment. Plus unwed parenthood, which already accounts for 40% of births in the United States.

The stakes seem absurdly high to dabble in “free love.” Yet free love is the new normal, extended even “to people who never wanted to shake off the old institutions, except to the extent of showing solidarity with friends who did.”

Witt bucks against all of this, but her unhappiness gives way to acceptance. Then curiosity.

So she embarks on a sexual quest that takes her to San Francisco, and to webcam stars, the orgasmic meditation outfit OneTaste, Kink.com shoots, polyamory, sex parties with names like Thunderwear IV, and, finally, a Burning Man fling with a guy named Lunar Fox.

None of this reads as especially erotic. The meditation meetings are cold and clinical when they’re not creepy. The public disgrace-themed porn shoots are disturbing, the orgies awkward, the triad love too complex. Burning Man feels a bit free and fun, but drug-heavy, and thus not exactly the world’s most sustainable game plan.

This doesn’t stop “Future Sex” from being a fascinating (and funny) read. It’s beautifully written. Brave. And there’s a tremendous satisfaction in seeing all this cultural confusion pinned down on the page.

But ultimately there’s nothing here to suggest a viable way out of the quagmire we find ourselves in, nothing that points the way to a more satisfying sex and dating life.

We’re left with all the same problems I encountered 15 years ago. And no solutions.

Henley is an award-winning journalist and the producer of a Canadian Broadcasting Corp. documentary about single women, “39.”

“Future Sex”

By Emily Witt

Farrar, Straus and Giroux: 224 pp., $25