The pattern suggests that he will come back but hopefully she has gained some insight when he left this time Nobody can predict the time he will return. Just like no one can predict if he definitely is going to return. The best guess is based on the past experience and he has continually returned once he has taken a break from the relationship. Hopefully she has had enough. That is the only way to end this completely. If she is just as motivated as he is to resume this relationship then there is a good chance that she will accept his promises. This suggests that she too wants to stay in this dysfunctional relationship and that may or may not have changed. Ask her what it will take to let him go; she knows.
If this is helpful press accept