It sounds like Joe Simpson had something to do with their breakup. Joe wants his daughters to be stars, but only on his terms.
When these two got married, Nick had a much larger career than Jessica. Joe Simpson told Nick that Jessica would not marry him if he wanted her to sign a prenuptial agreement. Nobody thought Jessica's career would explode like it has. Now Nick is entitled to half of everything she earned during the time they were together, and it bein California, he has a good shot at getting paid alimony. In that case, Joe outsmarted himself.