Girl's Behavior

Does she like me or does she flirt for attention?

I am a guy, 21. She is 25. We know each other for around three months as we follow the same course. After the first time we met, she already acted flirtatious: she played footsies with me, pushed her body towards mine when we were walking together towards the train station and we called and met around five times for our part of a group assignment, had some nice conversations about other things too and in my opinion I made it kind of clear that I find her interesting. After that group assignment was finished, I thought that we would probably never talk again. And I did not really care as I found out she had a boyfriend (lock screen picture, etc.), although she did never tell me. However, she started messaging me for help for homework, which she still does sometimes. We called so I could explain it to her. I tried to keep everything as professionally as possible as it felt unethical to become too close with her as I knew she had a boyfriend. When she came to wait with me before class started, and asked me about other things than homework, I tried to react evasive and shy. This is very difficult as I actually like her and she gives me the look quite regularly. She also has a very strong perfume with a very nice vanilla scent, which plays with my mind as I can still smell it now. For only wanting help with her homework, I consider this kind of flirting quite aggressive, so I think there's more although I find it difficult to believe that she actually likes me. The way she gives me the look and plays with her hair is obvious enough that it looks staged. What I would like to know is: why does she act the way she does and how should I react?

Does she like me or does she flirt for attention?
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