(this post is not meant to be offensive to men. there are lots of nice men. but some of them suck.)
I need to give the reader more clues that the bad guy is bad.
So. What are the little things that a man could do that tells us He Is Not A Gentleman?
-buying himself an icecream and not asking if she wants one.
-laying his jacket over a wet park bench, but sitting on it himself, leaving her to get wet.
-when she complains about the above two points, he tells her she's just being over emotional.