Why is he doing this??

i like this guy SO much. ive liked him since october and for all these months weve been talking. Everytime someone asks him if he likes me he always says "I don't know" and he smiles and blushes and stuff and were together a lot at school so everyone thinks were already going out. We've had some amazing times together but then there are other times when he hurts me so much, like I don't think he likes me. His friends are like his life, when were alone it looks like he loves me but when his friends are there hes so distant with me, i know he's shy and all his friends tell me he likes "you but he doesnt want anyone to know" times. the problem is that theres another girl who he added on facebook n shes his friends cousin who lives kinda far, doesnt go to out school n this idiot introduced the so he could get some alcohol off my guy n he said dont worry my cousin doesnt like him but then he added her on facebook and all these days weve been chilling things are good.. whys he doing this?