How do I help my friend move on from bad marriage and guilt for wanting to leave?

My friend can't seem to stay divorced from needy wife. She divorced him twice and then wanted him back. He divorced her and felt overwhelmed with guilt and went back after she pleaded. How do I help him see that he is with her for wrong reasons? Only good reason to be with her is if he loves her. They do not talk. They are just living together in "quiet desperation."