I dont understand Girls anymore.

Okay, so there was this girl in my geometry class that was pretty. We never talked much but we did talk and when we talked i only spoke a few words. One day on facebook i posted that i found new friends and how they made a poster of me and ihow much i appreicate them. I told them they were my best friend. The girl commented "You are one of my best friends too" Then on the last day of the semester, we had a party in class and we took a few pictures in class. She did tell me she is gonna post it on FB but never dead. Thats irrelavant right now. But later on she said. "Your my best friend now." I was like wtf? I remember last year when a girl said i was her "best friend", she loved me as in she tought i was cute and ya. The other girl i was talking about still dosent talk to me, instead she just likes the posts i post on facebook. In school she ignores me with her boyfriend not saying hi once. I dont get them anymore. What is it with this world?