Well, there are many ways to figure this out: First of all, if youre asking about the issue, it must be that youre having the feeling she isn't interested anymore, and usually your gut feeling is right. Id say, if she's distant, makes excuses to not spend time with you, if she's suddenly more aggressive and/or mean, if she demands more time away from you...these are just a few. Another big one is if she's less affectionate, and was once warm and loving towards you, but no longer is. Hope this helped.