I am speaking just for myself here. If my partner, even one I was madly in love with, came to me and confessed to cheating while we were monogamous, I wouldn't be that upset. I have never cheated on anyone, and I know for other people it sucks big time, but for me it's like a "whatever." Disappointed, but nothing to break up over and not surprised.

I did get fairly upset when my ex said he cheated on me, but that was not because of the cheating. It was because from the beginning when we discussed what kind of relationship we wanted, I asked him how he felt about open. He virtue signaled about how monogamy was the only way and made me feel bad for even asking, so I complied and was faithful. He cheated within 3 weeks.

It was the hypocrisy, not the cheating. Same with those "wife guys" who cheat. I'll admit, I can't look at John Mulaney the same anymore either, and for his wife it was a deal-breaker. But for me, it might only be because of all his virtue signaling.

I would honestly be more upset about a partner lying to me about liking something about me than cheating, which people find socially acceptable because those are "white lies." I would also be way more hurt by them being more attracted to/masturbating regularly to someone else they know.

I just couldn't bring myself to care very much about an affair my partner is honest about, especially if they had no emotional connection, no lying/gaslighting about it, etc..

Edit: To be extra clear, this isn't about acts with others within the bounds of an open relationship. Cheating is about breaking the rules of a relationship.

Edit 2: I have to clarify again it seems. CHEATING: BREAKING THE RULES OF A RELATIONSHIP BY BEING WITH ANOTHER PERSON SEXUALLY OR EMOTIONALLY. An open relationship is not cheating. I described only monogamous relationships in my post and contrasted them from open relationships. Please do not comment "this is talking about open relationships."

Open relationship: "You can see/sleep with/sext other people." they do it (no problem!)

Cheating: "Let's not see/sleep with/sext other people." they do it anyway (this is a problem, but not unforgivable to me)

No, I do not want a one-sided open relationship. I think most people who are open to these arrangements would also find this insulting and a dealbreaker. Most people in general want monogamy, and if you expect that of me, I expect that of you.