After six years of the security, support, and occasional suffocation that comes with a long-term monogamous relationship, I recently became single for the first time as an adult out of college. I knew dating again would be a strange and possibly emotionally difficult experience after so long with one person. But what I didn’t expect, and what nobody warned me about, was the sexism.

With feminism almost universally embraced, I had long assumed that anyone I’d be interested in hanging out with would know that the traditional, heterosexual dating rules are ridiculous. And why play some outdated game when you’ve absolutely no intention of starting a serious relationship?

The first time I met someone I was interested in post-break-up, none of those rules were relevant. We had sex, texted, and hung out without counting the hours between messages or playing hard to get. The second time, however, I was not so lucky. In a scenario familiar to millions of people, yet honestly surprising to me, I had sex with a guy (we’ll call him Dan) and never heard from him again. I didn’t know him well and certainly wasn’t emotionally invested, but the interaction still rankled me. We’d got on incredibly well and, for all the nonchalance endemic to casual hook ups, sex is an unavoidably intimate experience. The radio silence post-coitus seemed strangely cold.

The shift in his behavior was particularly striking because it runs so counter to most conventional adult behavior. In general, it’s pretty easy to read relationships. I can tell when a connection over drinks turns a colleague into a friend, or when you’re putting in the time with a family acquaintance and you just don’t jell. Even when the spark’s not totally there, polite society dictates a certain common courtesy. Hence the friendliness that oils our interactions with fitness instructors, former co-workers, friends-of-friends, and hairdressers. So why not people we sleep with?

But while friends were quick to call Dan a jerk, it’s not fair to wave off this behavior as straightforward rudeness. He didn’t seem particularly like a jerk, and almost certainly doesn’t think of himself as one. Ultimately, it seems women-whom-you’ve-had-sex-with are the only category of people straight men aren’t expected to treat cordially. This deep-seated sexism comes alongside various other problematic assumptions—that sex is something women give to men, that women always want relationships, that talking about emotions in connection to sex is “crazy”—that still seem to permeate heterosexual sexual relations. And that left me, a hard-core feminist in 2016, feeling like a cow that had given away the milk for free.

Yup, those sexist dating rules are still around

Perhaps it was naïve of me to assume dating culture had sorted out its sexist hang ups while I was blithely enmeshed in my own monogamous relationship. Kathleen Bogle, a sociology professor at La Salle University who has written about hook-up culture, confirms that despite progress on some feminist issues, misogynist sexual standards remain the norm. Tinder may have revolutionized how we meet people, but those threads of sexism have stubbornly remained the same.

This refusal to move past patriarchal stereotypes is surprising given young people’s progressive attitudes on other social issues, like LGBT rights. “It’s like day and night the conversation it would’ve been 20 years ago versus now when it comes to gay rights,” Bogle says. “But with the conversation on dating, hook-up culture, and sexual behavior, you still see that mentality of calling someone a slut, calling someone a hoe.”

Indeed, dating today still reflects some attitudes from when the practice first began in the early 1900s. Moira Weigel, a PhD candidate in comparative literature at Yale University, has written a book on the history of dating. When it first began, she says, dating was a way for working-class women of limited means to find husbands. Men had the wages to buy dinner (and, ultimately, a lifetime of financial security), so dating became a way for women to attract male attention and gain access to wealth.

“At a really deep level, even though I hope we’re moving beyond this in some way, there’s still the idea that dating is like work for women and recreation for men,” Weigel says. “Sex is a kind of work women do to get attention or affection, and men are the ones who have that to give.”

This explains the idea that sex is something women give men, as well as the widespread assumption that women are eager for committed relationships whereas men are only interested in sex.

“People often end up being bigger assholes than they have to because there’s always this assumption that a woman wants more,” Weigel says. “People treat people they’ve had sex with much worse than they treat people they’ve had a coffee with. It makes no sense that you have to be so rude, but I think it does come out of these expectations, where it’s like ‘Oh, if you spoke to a woman after having sex, she would expect you to father her child.’”

Lisa Wade, a sociology professor at Occidental College with a forthcoming book on college hook-up culture, says that this mentality also drives women to become prematurely detached in their sexual relations. “They know that men will latch on to any sign that they’re being friendly as proof they’re pathetic and want to be in a relationship,” she adds.

As a culture, we’ve elected to celebrate the supposedly male perspective of detachment, says Wade, and to enhance it to an emotionally cold extreme. And so while casual sex is now standard, having any feelings or concerns about such sex is seen as weird. “People are very embarrassed by emotion and by caring,” says Weigel.

Meanwhile, women who complain about how they’ve been treated or ask a sexual partner about their relationship are dismissed as “crazy.” Despite the term’s established connections to sexist stigma, Bogle says this idea still strongly resonates among young people.

It’s bad for men too

As is often the case with sexism, contemporary attitudes toward sex aren’t great for men either. Contrary to the stereotype, deep down, plenty of men don’t actually want a lot of meaningless sexual encounters.

There’s tremendous pressure on men to have sex when it’s available—“just as women get slut-shamed, men get shamed in that direction,” Bogle says—and to be unemotional in these relations. But in reality, men and women don’t have such wildly different desires. Wade says she remembers one young man talking about how easy it was to get blowjobs. “On the surface they’re very pleasurable,” he told her. “But it didn’t feel good.”

We’ve only just begun to scratch the surface in terms of how these stereotypes hurt men. For example, researchers recently found that erectile dysfunction in men under 40 is far more common than previously thought. Matt Hunter, who co-founded the Cambyo Project to honestly talk about and improve sex lives, wrote about how this attitude towards sex contributed to his own erectile dysfunction issues. “It didn’t have much to do with enjoying the sex, creating pleasure, or loving another person. It was more about the conquest, the story for my ‘bros,’ and a notch on the ol’ bedpost,” he wrote.

Weigel also points out that Neil Strauss, the author of The Game (“this perfect death dance of heterosexual stereotypes”) had to go to therapy for sex addiction. “Yeah, being a sociopath and pretending you have no feelings isn’t good for long-term happiness,” she adds.

Changing the dating conversation

Ultimately, I think what’s most surprising about sexism in dating is how reluctant we are to talk about it. The dating world is the last openly sexist area of society we’re all expected to ignore. We may swap horror stories about “the game” and “jerks,” but we rarely acknowledge the misogynistic attitudes behind such behavior. And even liberal, self-proclaimed feminist men can treat the women they sleep with coldly and not notice any incongruity.

Not sure if you’re part of the problem? Here’s an easy rule of thumb: Treat your sexual partners in such a way that, were you for whatever reason to end up working together, you wouldn’t feel awkward or embarrassed. In other words, just be nice. And if you do suddenly change your opinion about someone, act like a grown up and be honest about it. (I recently told a guy I’d been on two dates with that I was getting more of a friendship vibe. It felt unusually frank for the New York dating-app scene, but he appreciated the honesty, and I was glad I had resisted the urge to ghost on him.)

Progress in the dating world can be particularly slow, says Bogle, because there’s no clear legislation to campaign for or authoritative body to go to with complaints. Weigel agrees, noting that the notion of widespread, pervasive sexism can be upsetting.

“People don’t want to think about their private lives in structural terms because it feels unfixable,” she says. ”It’s very discouraging to think what you find frustrating in your private romantic life might be the result of huge economic and social forces that are beyond your individual control. Everyone just wants to know what they personally can do, which is really understandable. But feminism is a political movement—it’s not something one person can do.”

Still, individual changes in behavior are a good start. Don’t be a jerk, don’t ghost, and don’t consider the people you have sex with any less worthy of your time and energy than the people you interact with in public. We’re all slightly vulnerable during sex. There’s no need to pretend to be emotionally dead the morning after.