>>1 dont back of. If she wants you to back off, thats selfish, and she is not really your friend.
Do ou want them to be together? If they are, you would be the you know, extra wheel?
I mean, its not nice to have your best friends dating. Its lonely ;-;
Anyway, I have a feeling she will move on. I mean tell her how you feel about them dating and say Im sorry I cant help.
Or you can try to help them get together but since the guy likes you it would be for nothing.
When they start dating, it would be lonely for you. You cant be as close as you were before.
Its all up to you, you can either help or dont help but since she is your best friend you can consider helping too.
Its a choice you have to make yourself
Good luck >~<