Seriously your only 16 years old. Of course your going to have little relationships that last for weeks or months and then move on to the next.... until you reach a certain maturity this won't change. If you don't like what this girl is doing, why put up with it? your 16 you have your whole life to find someone who will repsect you and not play games with you. Your too young to be worrying over some girl who herself doesn't even know what she wants!
If you can't handle the thorns, don't crave the rose!!