not unless you trust her ;)
depends...from where
no because then your girlfriend would be cheating on you with your friend and you will be mad
The answer is in the question, my young padawan.
Only if you are a lesbian too
yes
Not if you trust her, and if you don't trust her you should be finding someone you do.
tell him he shouldn't let a girl get between you & him because in then end she might break his heart but you'll always be there to help & if she can not apreciate his friends then she is not a true girlfriend
no you should never let your girlfriend use you even if it is willingly, cause he might use you unwillingly withought you knowing, if that makes sense...well, no u shouldn't let her.
Did you not know he had a girlfriend? If he was hiding it from you... i'd say slap him/kick him in the balls and let his girlfriend know what he did.
you can beat him up, or let her choose If you trust your girlfriend and the two of you have a good relationship, it should not matter.
depends if you trust her but holding her back wont make her happy with you
Hell no what u thinking there will always be problems