I think she just want you to give up, cuz who knows if that guy is her bf or not, maybe she just lying to get you stop going after her. On the other hand, i do not think comparing yourself to the guy will do you any good because very likely the girl likes the guy not because of all those appearance, but more of a feeling type of things.
I am not telling you to give up or anything, but just be prepare for the worse case senario.
One more advice, if you really like the girl. GO FOR IT! Think of this: 10 years from now, would you regret for not going all out? If you think you will then i suggest you do everything you can to win her heart, who knows what will happen. Even if things don't work out, you have already tried your best.
Good Luck and please do let us know what happen after
