#1 She loves you for who you are
Love is not about changing yourself for someone. If she loves you for who you are, and she accepts you, along with your flaws and imperfections, then she is indeed the best girl for you. At the same time, if you think you can work on some of your own flaws, for the betterment of your relationship, nothing better than that. But forcing someone to change his/her habits, likes, and interests, is not what true love's all about.
#2 She understands that you have your own friends and family too
If your girlfriend understands the fact that before meeting her, or before getting into relationship with her, you had your own life – your family, your friends, and your work, and you still have your family, your friends, and work, and she doesn’t demands the entire 24 hours of your day, then she is really the girl for you. Moreover, if she gets along well with your family and friends, and loves spending time with them, she is certainly the coolest.