Guys, Why would a guy ignore the girl he likes?

So there is a guy who used to stare at me and with time he attracted me so I started making eye contact too ! I thought he was shy or insecure to make a move I thought I should take it to a new Lev and make a move... I started being around him and making eye contact but now he started avoiding me like today I was at the stairs looking at him he saw Me and did nothing at all he 100% ignored ! Is it that he lost interest? Or I freaked him out? Or he's playing hard to get because now he knows I want him? Why would he ignore me if he likes me what does he expect to achieve from that? What should I do now?
Guys, Why would a guy ignore the girl he likes?
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