Is she tired of waiting for me to ask her out?

This girl has had a crush on me since last year. I only started to like her later part of the year. We started to talk more and get closer and everything seemed like it was going well. But suddenly her interest stopped. She stopped talking to me as well, not avoiding though. At that time another guy started to show interest in her as well but I don't think she liked him. Thinking she didn't like me anymore, I moved on.
After the two month vacation in November and December, this year, she suddenly started to show interest in me again. I also started to show interest and we started to get really close again. However, this week she stopped showing interest again. I did intiate a conversation once with her and she seemed fine, not angry or frustrated at me or anything. But she just stopped showing interest, including looking at me even when I was close by. What could be the reason for this?
Is she tired of waiting for me to ask her out?
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