Sometimes I have trouble figuring out social dynamics and stuff. I'm very good at noticing details of body language and demeanor but I am terrible at actually deciphering them, so I can tell when something's wrong, but not know why.
I (18F) started going to a new school a few months back. On separate occasions, I met a guy "Logan" (17M) and a girl "Lucy" (17F) and I would hang out with them sometimes. They are the only two people I'm friends with there so far. They didn't know each other for a while though.
Anyway one day I was sitting at a picnic table chatting with Logan and we were really getting along super well at this point, when I saw Lucy walk by. I didn't want to ignore her but I didn't want to leave behind Logan so I invited her to sit with us and immediately the atmosphere shifted. Logan got a weird look on his face and his conversation got much less outgoing than he had been right before. But if you had never met him you probably wouldn't notice anything amiss.
We all hung out for a few minutes during which I was totally confused and then we left for classes. I asked him later what happened and if I did something wrong and he said nothing happened, everything was fine with him but I don't think he's being completely honest.
He's been perfectly normal since then but we also haven't run into Lucy again yet either. I'm positive they never met before that day so I'm not really sure why he was secretly miffed that I invited her?