Why would a girl reject you, but then seem insecure at the same time?

this girl said she didn't like me as any more than a friend, but then she seemed insecure too or like scared I was "out to get her" or something, when I just wanted to be mature about the situation and be a good guy for her. I don't understand why things are so whack or why I seem to scare her, or why she doesn't seem to like me, when it really seemed like she could have. any thoughts?
Why would a girl reject you, but then seem insecure at the same time?
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