Why was my friends with benefits acting nervous and shy with me?

He is usually really outgoing and he talks the most I'm a little shy. but I do talk to him. the most recent time we hung out he was nervous and shy. it was weird. this time I was outgoing and I was being myself. do u think he's into me. we are so confusing when I'm me nervous around he's is outgoing but when I'm outgoing he's nervous.
Why was my friends with benefits acting nervous and shy with me?
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