I doubt that he’s actually pulling out.
First, the sequels haven’t been officially confirmed. Second, he’s probably contractually bound to do them and he would have a hard time backing out on his own. Third, the studio and his reps have yet to even suggest this is happening. Fourth, the reason being given—that his wife wants him out because of what Christian does—MAKES NO SENSE.
The “plots” of the books haven’t changed since he signed on. Jamie has been playing the part of Paul Spector in The Fall; Paul is a serial rapist and serial killer. AFAIK: she hasn’t demanded that he quit the series. It seems like she would have wanted him out of that if she was really against his playing a man who is violent toward women. And Amelia is an actress and had a small role in the movie Quills, a fictionalization of the life and proclivities of Marquis de Sade, whose name is where the terms sadism and sadomasochism come from. So this whole thing makes no sense.
What it seems like is a way to create a lot of drama and a way to make people feel okay with harassing & hating Amelia.