"In a way I think he feels responsible."

I wouldn't be surprised if he did, since all three of them made the decision to marry the marks. As a direct result, the woman he once loved became a purely sociopathic all-devouring succubus who has sex with anyone she finds desirable, and uses her powers to make them have sex with her (and be addicted) even if they don't want to.

Not entirely rational, but it would be an understandable feeling.