MJ, you're killing me! For sure #1, #3, and #4 are very similar in that the men were married. They're different in what info the men conveyed to the side piece. In #1, the man simply didn't tell her he was married, so she didn't know he was married. In #3, the man claimed he was separated. In #4, the main told her he was divorced.

But what this is doing is illustrating that I really struggled to come up with 5 situations where I thought it was ok for a sidepiece to be involved in cheating. I had to really split hairs, as you point out, to even come up with 5!

The reason I struggled is because I really do find it hard to think of many defensible reasons for a side piece to knowingly be in a relationship that lets a person cheat. I've heard situations where the side piece didn't know the guy was married, then after she found out, she decided to keep on with the affair because by the she was in love and couldn't help herself. That definitely didn't make it on my list of 5 situations!