>>23629120>>23629460>>23629588To be fair, let's think of the boyfriend as a fellow bro. It's not very bro-like of us if we kept on hounding his girlfriend, not very gentlemanly of us if we make a fellow bro insecure about his relationship. So the best option any decent bros would have is to not watch the girl anymore and wish them all the best in their relationship.
If you really think hard about it, it's just common courtesy and doesn't even have to do with cucking.