I think when it becomes difficult to justify someone's behaviour or responsibility, it often means, there no satisfactory answer in any way. Best thing to do, is just let it be. LIke not trying to solve it, figure it out or try reason with her. Let time get ahead instead. These things can be dragged forever, but won't be worth it. If she is treating you like not as her friend, then don't act or expect she is one. Certain situations and problemes are unfortunate but are there to show true colors.