However you feel about your partner having sex with someone else — whether you're terrified or turned on (or somewhere in between) — there are many people out there who get off on the thought of their S.O. getting it on with a third party.
There's even a kink devoted to that idea: cuckolding. Generally, this refers to when a straight man watches his wife or girlfriend having sex with another man. Maybe you've heard the word "cuck" recently? It's been co-opted by the so-called "alt-right" to describe a weak man. This is because the kink and that term can have a humiliation aspect (though the "alt-right" use is a derogatory take that the kink community doesn't support). "Indeed, much of cuckolding porn is focused on submissive themes, where the husband has a tiny penis compared to the hung guy that fucks his wife," says Michael Aaron, PhD, a kink-friendly therapist in New York City and author of Modern Sexuality: The Truth about Sex and Relationships.
But you don't have to be a straight man, or even a full-blown kinkster, to be into this. People of all genders and sexual orientations can be turned on by the idea of their partner having sex with someone else. I've experienced it. While I don't want my male partner to cheat on me (since that would involve deception), the idea of him with another woman — especially if I'm there to watch — turns me on in a very primal way. And this is not an unusual fantasy, according to Madeleine Castellanos, MD, an NYC-based sex therapist and author of Wanting to Want: What Kills Your Sex Life and How to Keep It Alive.