What do you do when youtr friend likes a girl but the girl doesn't like him but instead she likes you?

You have to be honest with your friend. Your friend may not speak to you for awhile, but will slowly come around. If you aren't sure about this person you both like and have no real intentions of having a relationship with him/her I would simply back off. If you are interested in this person, then please be honest with your friend. If you have a very close friendship with your friend no man or women is worth losing that friendship over.