My friend went through so much drama with her M BF years ago before the broke up for good. Gag, wish there was a male version of the word mistress because he cannot truly be a BF if he has a WIFE!
Anywhoo, she did some work on herself and states she will never be an OW ever again.
Then she got with her now XBF. He was a real dog. He cheated over and over. She has actually caught him in the act in their bed with more than one OW. Her first statement that I had to set her straight on was after they broke up for the millionth time. He is "engaged" (to make her jealous) to a new GF. She told me, "I wish these F...ing whores would just leave MY BF and baby's father alone. I know we could make it work if they would stop throwing themselves at him. And as for this whore, I should kick her ass for dating a man with a GF and a baby."
I pointed that his intended had a ring which makes her his legitimate woman.
Then she asked, "What did I ever do to deserve this?"
I do try to give her gentle 2 X 4s. But sometimes her refusal to see what she does to contribute to her own self destruct path is frustrating. I also told her I cannot ever again be friend's with her if she were ever the OW with another M man.
All you can do is pray for them and try to support them with some gentle and not so gentle truth.