2 - he initiated his divorce and his kids are mad at him AND his ex. This worries me even though his version of their marriage makes me think he was justified in leaving still we know WASs can spin tales. Maybe he was difficult to live with (see number 3 below). Still, when I made a joke with him about the black dude in my bed (my son's 3 month old all black kitten) it evolved into him saying he just couldnt date more than one person at a time - reassuring comment.
Being that this is the divorce busting site , I think I would agree with devvo, this could be a concern.
Although maybe she was cheating on him and that was his boundary.
For me I would need a lot more info, I do not believe many people learn anything from getting divorced.