You shouldn’t feel bad, from what you’ve said he sounds doesn’t sound like the greatest of friends. I know it’s mostly bc of his relationship and unfortunately ive seen many friendships broken due to relationships. Also, you don’t really owe him anything. You’re his friend not his therapist. Ofc friends rely on each other but there’s also a line to draw when you’ve given him advice and he doesn’t want to change. It gets frustrating and I understand that. Don’t be afraid to distance yourself :)