Guy's Behavior

Why did he act this way?

(Backstory) Me and this guy basically being playful towards each other last week that we know we like each other. Neither of us has saying anything but we know. We work together, we both went outside to get food, he came back inside first minutes later I did. I went to the area where we are sitting I see him standing. I grab a chair thinking theirs no more chairs that’s why he standing. When I get their I see theirs a chair, ends up sitting in the one I brought. (The question) Why did he not sit in the chair that was already their?

Why did he act this way?
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