Quote:
I'm often afraid of being perceived as hitting on friends' girlfriends.
Perception is exactly that. Just because someone thinks something, doesn't make it fact. The joy of being self-assured is that if someone has a problem with you being flirty around their gf and you aren't doing it on purpose to get with her, the problem is all theirs. You're innocent, you wouldn't do anything even if she threw herself at you cos she is with your friend. You can't put a stopper on your personality because some dude is insecure or overprotective of his girl.
As long as you're just being yourself and not actually trying to hit on them there's no problem, I mean your friends should know what you're like and trust both their gfs (and you) enough not to get jealous/suspicious/whatever. You can't change your personality to suit everyone at once now, can you? Just be yourself.