Can I ask what your ages are? Because if she has never loved anyone in a relationship before, I am just getting the impression she is fairly young. Things that are new tend to scare us. And if she has such feelings for you that she thinks she might love you, it might not be the feelings she is afraid of, but what that might mean to her future (school, work, etc).
Also, you say you are not going to change, but everyone changes throughout their life. Experiences and how we handle them constantly change us.
Good luck.
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