The threesome has spent millennia at the top of the sexual fantasy charts, immortalized in movies, half-joked about at dinner tables, and held onto by the majority of people who will never actually pursue one.

According to research by Dr. Justin Lehmiller, a research fellow at the Kinsey Institute who surveyed more than 4,000 Americans for his book Tell Me What You Want, 89% of participants had fantasized about a threesome at least once, making it the single most common sexual fantasy across genders. A nationally representative study found that only 10% of women and 18% of men had actually had one. The math on that is instructive.

In your head, a threesome goes exactly the way you want it to. Nobody’s feelings get hurt, nobody gets left out, and the whole thing wraps up without any awkward logistics. The real thing comes with all of that, plus complications that weren’t even a thought at all.

Why Threesomes Are Usually Better in Your Head Than in Real Life

Part of what keeps the fantasy alive is how thoroughly pop culture has packaged it. Movies, television, and pornography have spent years presenting the threesome as a seamless event that concludes without anyone feeling weird about it. That version bears almost no resemblance to what sex therapists and researchers actually hear from people who’ve tried it.

Lehmiller’s research associated group sex fantasies with the desire to feel completely wanted, to be the center of attention in a way that ordinary life doesn’t provide. The imagination delivers that without asking anything in return. In reality, these are people with real feelings about what’s happening. That changes the experience considerably.

Sex therapists point out that jealousy is the complication fantasy conveniently skips. Imagining your partner with someone else and watching it happen in the same room are two experiences with very little overlap. Many couples who went through with it report that the emotional reality afterward was unlike anything they had anticipated.

The fantasy can stay exactly where it is. Sex researchers are consistent on this point. Fantasies serve a psychological function without requiring execution, and sometimes the version in your head is delivering something that reality, with all its logistics and feelings, couldn’t replicate anyway. The threesome you’ve been imagining is probably better than the one you’d actually have, and that’s completely normal.

That’s just how fantasies work.