It can be hard to figure out the line between being a supportive friend and calling out bad behavior. This truth is multiplied when it comes to the romantic relationships of a close friend, everyone has different priorities and moral boundaries when it comes to romance, and finding the space between honesty and acceptance can be incredibly hard with close friends.
The subject of cheating is deeply controversial for many. Some people will turn a blind eye to a friend's cheating, because they don't believe it's their place to meddle. Others, however, feel a moral responsibility to confront the cheater or even reveal the cheating to their friend's betrayed partner.
"AITA for refusing to be my best friend's best man when he marries his second wife, who is his former mistress?"
"My best friend is getting married to his second wife, who was his mistress when he was still married to his first wife. He asked me to be his best man and I refused."