Leave already. He Ain't Gonna Change

I have a friend in a strained relationship.  Strained to the point, she doesn't live with her husband anymore.  The two have not officially divorced but considering they have not lived under the same roof in over a year, they might as well go ahead and make it official.  For whatever reason, they refuse to do so.  Also, she refuses to stop giving him chances to upset her.  If he wasn't doing right, when you were together, he damn sure ain't gonna do right when you're not.  My biggest problem with the situation is their kids.  He'll make plans to do something with the kids and then pull out at the last minute without a reasonable excuse.  I could understand a life/death situation or going to work trying to make more money to support the family.  No.  This nigga bailed on his kids to ride with another nigga out of town.  Really?  You ditched yo kids to be a dude's side bitch and got absolutely nothing out of the deal?  Stupidity at its finest.  I've told her to leave his stupid ass several times but she hasn't.  Guess she's gonna keep dealing with his non-changing ass.