@digomaw,
Quote:I have this friend of mine that claims she has a boyfriend.
So she is either telling you the truth and if so, then you should leave well enough alone. (I am guessing the reason you are curious is that you are interested in her.) If she is lying to you, then it seems to me the reason would be that she wants to discourage you from getting any ideas about dating her. In other words, she is not interested in you that way.
In either case, I think you should chalk this one up as a loss, simply be content with having her as a friend, and look elsewhere for companionship.