Saw a guy I somewhat know and he had a dramatic reaction to seeing me in public?

I saw a guy the other day who I haven’t seen in a long time. He was on the top floor but I was on ground floor and from where he was he could see the ground floor through a glass panel.

so he is with another girl and she walks on out of sight but he stops to take a look at the ground floor for a second, takes a scan and is about to walk off, but when he sees me so unexpectedly, he slows down his walking pace immediately. Then turns around, walks a few more steps forward where he can see me a bit clearer, and then sits down on a one knee to get a better look at me while putting his face closer to the glass panel. He then quickly got up to his feet while watching me but seemed quite rushed and then turned around and walked away to where the girl would be, he was talking to her as well. I’m *guessing* she saw him in the floor and asked “What the heck are you doing?” or something along those lines.

Why do you think he reacted like this?

Updates
2 mo
by the way this encounter was quite quick, only lasted about 10 seconds or so
Saw a guy I somewhat know and he had a dramatic reaction to seeing me in public?
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