My wife has had at least 3 boyfriends that I am aware of since we have been married. For me it is quite the turn on to know she has been out and fucked senseless coming home with cum filled panties. I have made love to her afterwards knowing she is full of another guys cum.
All I will say is that when a long term girlfriend confessed to playing around the hurt, anger and extreme disappointment was superceded by an unexpected massive arousal. We stayed together and enjoyed an expansively new sexual side to our relationship.