I said bye to a guy to whom I was talking while walking to my car but he didn't reply back. Why?

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Ok it might that he didn't hear me because I got a lot of feedback from my friends that my voice is not audible whenever I say bye to them or smth and it was also a windy day so maybe.
Ok so the next day this guy and I are walking again but now he says " see you later" , I just want to know if he likes me or not? He never talks to any other girl in my class but is always the charmer of the class like the girls like him.
I said bye to a guy to whom I was talking while walking to my car but he didn't reply back. Why?
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