What does it mean if a guy gets upset that I don't say hi to him?

so me and this guy started talking over summer and we really got along and he would tell me all the time how much he liked talking to me and then we stopped talking for a little bit becuase I thought he didn't want to anymore and then when school started I would just walk past him when I saw him and then he texted me and told me he gets upset that I don't say hi to him and he even told my friend that I don't say hi to him and that he looks at me all the time to say hi but I don't look at him
What does it mean if a guy gets upset that I don't say hi to him?
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