Whats wrong with my gf now its ex , really doesnt understands ?

well i got a GF ,im 16 , and my gf is 16 , my gf dump me , she said she wana concentred on studies ,so i let it go, but now she always look at me , does she like me ? , and looking at her behaviour , she seems wana be friends with me , lastime she ask me to go out but she go out without me , she doesnt ask me to go , maybe shes changing her mind , but i hate it shes trying to be nice to my best friend , did she wana make me jealous ? what should i do , i love her very much =( , but i tink she doesnt like me anymore , i really sure that i doesnt make mistake