Personally I think staying friends with exes/past sexual partners is fine as long as Im 100% sure I dont have a feeling towards them anymore, but never ever kept regular contact with any of them.
How do you deal with the fact that bf still hangs out with ex/girls he's slept with alone or as in a group? (I guess many people would say if they have mutual friends and have to hang out together as a group regularly there's nothing you can do about it.)
Any red flags I should take notes of?