haven't tried chatting up someone elses girlfriend blatently infront of the dude, not the nicest of things to be doing. There's plenty of other girls out there, no need to ruin this guys night/life.

Generally guys won't do shit because you're not all over the girl and you're just being friendly, but, if you're all up on someone's girl you deserve to get a bad reaction from the guy.

If someone came out chatting up my girl (which has happened before) I usually leave him to it and go off and have fun or just out 'game' him. If she's a bitch and is gonna go off with some other guy, fuck her. Whats happened in the past though is he's just some loser and me just having fun and ignoring it seems to 'work' better.