That...doesn't sound like a marriage. It sounds like they rushed into a marriage while caught up in infatuation but are now realizing that they'd rather be with other people.
If she wants to stay with him, she's probably going to have to give an ultimatum along the lines of, "Yes, I made a mistake, but I STOPPED. Now YOU need to stop or there's no point in being married. You can be friends with your ex-girlfriends without spending hours hanging out with them - that's not part of a commitment."
Just out of curiosity, what age range are they in? Because he sounds really, really immature.