Don't be friends with them. Simple as that if they are truly your friend they will respect you and your boyfriend and not get in the way of your relationship.
you should dump him because he's suppost to be comitted to you only and if your friend flirts back you shouldn't be her friend because that's not a true friend
It is definitely not okay! You shouldn't flirt with other people. It relays a message of immaturity and poor self-esteem. Your boyfriend could also break up with you!
If she's really your friend, then you don't. Friendship is just another kind of love and love means doing what's within our reach so that our partner feels happy. Do you think your friend will...