because your best friend is not your best friend.......and well often people want the forbidden fruit, i.e. their closest friend's girlfriend........i suggest you break up with that girl and find a new friend as well.
make your girlfriend jealous
You continue to be his best friend and nothing more. As long as he's with another girl, he's not with you. You should make sure to enforce that. You do not want to become "the other woman" in a cheating relationship. Also it would show him not to be a trustworthy person if he is willing to cheat on his girlfriend with you. If he really is in love with you and not with his girlfriend, he will leave her for you. Until that happens, you continue to support him as the best friend you've always been.
date her BEST friend.
Sounds like she is the one who needs to make a choice. Let them have each other. Find a new friend and girlfriend who come with less baggage and drama.
Girlfriend/Boyfriend is someone you have sex with, a friend is someone who has a friendship with you.
The best way to make a friend is to be a friend.
Doing that doesn't make you much of a friend. Does he know how little of a friend you really are?
Set him straight, make it clear you're single, and ask your friend why she lied.
You cannot much than care for them. Caring for a best friend till they love you is a common phenomenon.
Well you can make him jelous.
he probally would talk about her and stare at her or make fun or talk bad about her. He will always want to hang around his best friend and his girlfriend, and he will constantly chat to his best friend and girlfriend to catch the attention of the girl he likes. Male dynamics :) *sigh*
Move on. No boy should get in the way of you and your best friend. It's not worst the hastle of you and your best mate having a fight over a boy. Trust me there's more boys out there. Some will probably make you happier then your best mates boyfriend ever will.