A few months ago, I discovered that my girlfriend at the time had actually been in a relationship with another guy for months before she met me. In short, I discovered that I was the "other man" with whom she was cheating on her boyfriend. I broke up with her, because dishonesty is a dealbreaker for me, and moved on with my life. My question: should I tell her boyfriend that she was kissing on me while they were together? It seems like he might have a right to know, but since I broke up with her months ago I'm concerned that telling the boyfriend now would just make it look to her like I'm trying to split them up out of spite, and to be honest I would feel very satisfied splitting them up. Am I ethically obligated to tell her boyfriend, or is my responsibility to minimize the amount of harm to all by not telling anybody?
--Flirted with the Wrong Chick
Dear Flirted with and Wronged Nick,
I would likely allow her to change and not tell him, but he may have a right to know. For me, when deciding whether to tell him, I would consider what is important to him. Like Luciana said, since you don't know the details of their relationship, you don't necessarily have the grounds to tell him; however, if I knew the guy and and I knew that he needed to know, then I would tell him. In my mind, if she weren't meeting his needs by not telling him, it would do more good than harm if he knew. Note that it depends on his needs, though. If it were me and I didn't know the guy, I probably wouldn't tell him.
I wouldn't tell him if I were in your shoes. As awful as it is that she cheated on him, you don't know the intimate details of their relationship. He might already know. They might have an open relationship. She might have changed since then and might be totally committed. Long story short, it isn't your place to interfere with someone's happiness, even if it's based in dishonesty. I don't think there's an easy ethical answer to your question, but personally I would rather hold my tongue than be the cause of anyone else's pain.