guy trouble?

i went on a school trip and there was this guy that i knew who went. we were in one class together last year but this year we had none. we reconnected at the school play and then we started flirting a little before the trip started. we had his head on my knee in the airport and on the way to our hotel we ended up holding hands. then next morning we went with our other friends to the place. the next night we walked around & he had his arm around my waist & we went back to his room (b/c i locked myself out of mine). the chaperones were hanging out nea rhis door & it was open (nuttin happened). for the next few days we hung out together with a small group of friends we me and him would flirt. sometimes he would get really flirty and put his hands on my butt. he's very sexual minded, as all guys are and we had a good time. but when the trip was over, its like it never happened. we carely talk in school and he doesnt flirt w/ me anymore. what happened? why did he change?did he like me?help!