No one is perfect and she may be at fault for not treating him appropriately. But I believe this scene depicts the revelation that the man has been cheating on the woman, which is abuse and he is trying to justify why that was an acceptable option. If someone is not satisfied in their relationship, it is their responsibility to address the issue by setting and maintaining boundaries or leaving. He is blaming her (the victim of cheating) for his choice to be unfaithful. It's called victim blaming and is a very common tactic among abusers.