Why does this guy avoid staring/looking at me now, but before stared non-stop and was smiling?

He seems kind of unhappy in general. I hope he’s ok. But I notice he avoids me now almost like I’m not even there. Before he would like stop in his tracks and stare and try talking to me.
Why does this guy avoid staring/looking at me now, but before stared non-stop and was smiling?
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