He has also recently started to call me dude a few times and bro once
Are you sure he knows you are a woman? lol
Anyway, he has a girlfriend and as was said in the previous post, if he really is flirting with you, then he is not respecting her. And if he does that with you, there is a good chance he is doing it with others too. I'd think most women would want better than that. And if that includes you, then you might want to steer clear of him.