Your girlfriend is not a whore, OP, she just doesn't match what you expect a relationship to be like. You want a steady relationship, to be her only one. From what you've said, she promises that, but also cares deeply for other guy friends.
Neither of you are in the wrong, but clearly as things stand you will not be happy with her. Odds are she'll change, but that could take 10-20 years. I suggest you remains friends with her, as you WILL get your heart broken many times before you ever get anywhere close to happiness with this girl, because from what I've heard, she doesn't seem to like to be told how to act.