John Wesley, Untitled (1991). Photo: John Wesley

“I have an important question about married life, which remains incomprehensible to me, but I am trying to understand,” I Gchatted my childhood friend Vanessa last week. She’s been with her husband for a decade. “When the hell do you masturbate?”

If a hobby is an activity pursued for pleasure, then masturbation is perhaps the hobby most of humanity shares. Though the prevalence of masturbation varies by age, most men and women in all age groups say they do it, and the majority of Americans of both genders continue to indulge at least up to age 60. But contrary to what you might think about handsy adolescents, today’s most frequent masturbators are between the ages of 25 and 29 — a group very much in the relationship stage of their lives. Born not long after Betty Dodson published her revolutionary masturbation how-to Sex for One (the 85-year-old leads female-masturbation workshops to this day), they were raised solidly in an age of sex-positive feminism, easily accessible erotica, and general sexual openness and transparency.

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Not that the role of masturbation in a sex-positive relationship is entirely clear. On the one hand, pioneers like Dodson have helped to align sexuality with self-empowerment, which has taught us to think of masturbation as a healthy element of a diverse sexual menu as opposed to a shameful, inadequate substitute for sex — even from day one in a fulfilling relationship. Most studies find that a big majority of married Americans report masturbating (and since it’s self-reporting, that probably undersells it). “Even if I had all the men in the world that I wanted in my bed, even if I had Ryan Gosling, I would still masturbate with sex toys,” French sex columnist Maïa Mazaurette recently told me. “I don’t want to go back to a world without plastic!”

On the other hand, well, masturbation is sort of inherently antisocial. Within the bounds of a relationship defined, in part, by both partners’ willingness to devote sexual energy to one another, it can be downright rude. Can we ever really get over the embarrassment of purely personal indulgence? Or take the indulgence of your partner as anything other than a rejection of you? Even if we want to be open, practically and emotionally, exposing deeply private habits to anyone — even the one you love — is reflexively uncomfortable. And hearing your girlfriend rev up her vibrator after saying she’s going to sleep early can be hard to shake. Just because everyone’s doing it doesn’t mean that the negotiations won’t be awkward or that the concessions will be easy to get used to.

The practicalities are particularly awkward in New York, where personal space is always at a premium. Vanessa spent half of her decade-long relationship cohabiting in a studio apartment: “The transition to the studio was way weirder for J.O.-ing than marriage was.” Why? “Masturbation is a statement of private space.” Seinfeld was wrong: The “master of his domain” is not the man who controls his urges but the one who controls his domain so thoroughly as to indulge any urge he wants inside of it. She who orgasms alone in a space is the one who truly owns it. (For the record, Vanessa’s secret is “three words: working from home.” Her name, and some others, have been changed.)

The “domain,” of course, is often metaphorical, especially among couples who seem to have figured this whole mess out: “Girl, sometimes I do it next to him,” said another married friend, who has been with her husband for 12 years. “Like the morning if he’s dozing. My favorite, purple vibrator. It’s pretty quiet.” If he wakes, he may try to initiate sex, but mostly he just says good morning and carries on. Meanwhile, a friend we’ll call Peter noted that masturbation relieves his boyfriend Ivan’s hangovers but not his. On weekend mornings, “I know he’s doing it when he hands me the dog and shuts the bedroom door.” Peter considers this a practical consideration; if the dog saw a hand moving rapidly, he’d try to play with it. “He always bites and pulls on dangling things,” Peter said of the dog. “Like the drawstring on my pants. I’m worried he’s going to bite one of our dicks someday.”

Of course, the real major hazard, even for a sex-positive couple, is that one person gets offended. Because even a theoretical coolness with open masturbation may not translate to reality for everyone. When Ivan’s sleeping, Peter occasionally finds himself hastily masturbating with the bathroom door closed, “which is definitely furtive.” (After Peter’s confession, Ivan interjected with horror: “But why the bathroom?! I use the TV room when you’re asleep. Big screen!”) “In sex you’re never ‘just enjoying yourself,’ ” my friend Greg observed. “Maybe this is the male perspective, but you sort of have to have some kind of plan but also be creative and improvisatory and so on. You have to self-regulate and be ‘present’ and ‘on.’ So sex, as fun as it is, is also kind of demanding. But masturbation is like a release from and contrast with all of that. It’s a sexy way of indulging in all the sorts of freedom and negligence that sex, paradoxically, excludes. You’re really, definitely not ‘on.’ You’re off. You’re so turned off, you’re turned on.” Greg, who is 30, masturbated steadily through his most recent romantic cohabitation but still considers the act too embarrassing to discuss voluntarily. “Masturbating is the sexual equivalent of eating a sleeve of Girl Scout cookies and watching Vanderpump Rules. Not to judge either of those things — that example is from my life.”

But — what kind of index of relationship happiness is masturbation? The relative importance is actually unclear. A 1991 study in the Journal of Sex Education and Therapy found that women who masturbate report better “marital satisfaction” than those who don’t, perhaps because women are less likely to orgasm from intercourse. Meanwhile, a 2014 study in the Journal of Sex & Marital Therapy found that married men who are bored with or distant from their wives report masturbating more than their happily married peers. As is the case with most sexual behaviors, the question is not what is happening but how (and many researchers point out that masturbation can be crucial in balancing partners’ occasionally disparate sex drives). In part, that’s because it’s as much a sexual exploration of autonomy as it is an autonomous sex act — a highly refined personal craft, honed and reinvented incrementally over the course of decades. How much can a routine that started before you learned to shave really say about adult relationships? Especially since, after a lifetime of solitary craftsmanship, masturbation can get, well, bizarre.

“Oh my God, I think I’m having a Pavlovian boner,” 33-year-old Ari said as he folded three pieces of Kleenex, using an “origami-like” linking technique to create the loop-shaped masturbation device that he has, since his teens, used to achieve what he calls a “soft-touch orgasm.” (A term he realized he’d never uttered out loud until that moment.) When a relationship of four years began to fall apart, he found himself “masturbating a lot.” As the relationship turned sexless, he fell into a pattern of waiting until his girlfriend fell asleep, then masturbating slowly and continuously with an origami Kleenex before climbing into bed beside her — as relationship stress mounted, he relied on the nocturnal jerk-off to help him fall asleep. After several months, they finally had sex, and his girlfriend noticed a scab on his dick. “I made some kind of excuse about cutting my penis somehow, but actually it was like when you have a cold and your nose gets chapped from blowing it.” Amid cheating accusations and confused WebMD searches, the pair split a few months later.

“We do masturbate in front of each other sometimes, mostly out of laziness,” said Dana, a 26-year-old who’s lived for three years in a 450-square-foot apartment with her boyfriend. I replied to a link to a satirical speech Mark Twain once gave comparing “onanism” to flatulence: “Among the best bred, the two arts are now indulged only in private — though by consent of the whole company” it is possible “to remove the embargo on the fundamental sigh.” Perhaps true love is being comfortable enough not only to fart, but to have slovenly orgasms on the sofa while your boyfriend is watching Game of Thrones. With a flurry of LOLs, Dana announced that this very scenario happened recently. “But I think it was Chopped.”

*This article appears in the January 26, 2015 issue of New York Magazine.