LOL okay funny coincidence here.
i was in the EXACT position like about 3 and half months ago, but it was the vice-versa to this.
the girl treated me so badly and of course she treated me pretty bad. but this went on for 6 and half months. we weren't ever officially together.
what he is doing is just having her around up until he can find someone else, someone who fits his description of "better"..
your friend KNOWS what's going on here, trust me she knows, but she seems to be a little more in love with the person that he could be rather than the person that he is.
whats going to happen, eventually, is that their going to ride it out till there's nothing left between them. he's just telling her things that she wants to hear, you know that... naturally, relationships can often confuse people instead of letting them see with logic.
you can't get mad at her, she's your friend your supposed to support her. but hey getting mad is part of being human... why am i saying this? its because with this state of mind that she's in she won't pay attention you. she will continue talking to him, that is if you tell her that he's not right for her and that he's just trying to get "some" off of her... don't worry she will get her good man sometime in the future.. i got my good girl and surprisingly im happy. just keep going as the loving caring friend that you are and you'll see that its never going to work out. remind her that not all guys are the same, there are good guys out there because once they are completely through she's going to treat the next guy like crap and Two Wrongs Don't Make A Right.
anyways, best of wishes for you and your friend.