I think it was right here in this line: And definitely no need to think about her feelings, wants, desires, or idiosyncrasies ie. he's a jackass.
Just because he gave her a ring, that didn't give him license to turn off his love for her. He's a grade A jackass. He wasn't even trying to be a friend, never mind a decent husband. He's a pure taker.
Hmmm, not a nice guy. Well, he got what he deserved.