You’re all adults. You’re old enough to decide who you sleep with, how many people you sleep with, and what you do in the bedroom. Unless you were raped, you can’t say you did something you didn’t want to do.

(Of course drugs or alcohol could influence your decision but it was your choice to put that into your body.)

You want to accuse your partner of cheating or being unfaithful because they had sex with someone else in front of you. But then, you had sex with the same person they did. You think it was ‘same sex’ so it doesn’t count. It still counts, your were all over each other.

If your primary partner has sex with the third person when you leave, it’s cheating. You did not discuss or agree to that. They did it behind your back. Neither one of them are faithful and cannot be trusted. Forget them.