I disagree. She is dating one of your good friends. You need to have more integrity. Don't flirt with her because she is off limits if she is with your friend. Of course he has a reason to be worried... you are flirting with his girlfriend. People cheat and he's probably worried that she will. Forget her because your friendship is probably more important. She is putting herself in a bad situation by having a boyfriend and flirting with one of his good friends. This can only end badly if you make a move.
