Why does this guy act weird around me now?

[Anonymous]

This guy is usually fine around other girls who are his friends or are strangers he has just met.

With my situation, he and I were friendly at first. He was a bit shy but then he started to act super excited whenever he was around me. Soon after that, he became quiet and nervous. He has such a serious demenour about him whenever I'm near. Why can't he be himself around me like before?

[Neurath]

He's restraining himself for fear of acting like a fool, being perceived as a fool or overstepping an invisible boundary. The longer he is left in the mode the wider the gap between you will become. If you are taken he will be respecting that boundary.

[1GuyOpinion]

He realize or know something about you. Something he don't like I guess.

Or maybe he think he fallen for you and feel weird about it.

[Klaatu51]

i guess he's started developing feelings towards u, and that's the reason behind his nervousness basically... happens with many guys ;-)