Why does he do THAT!!!?

This guy and I like each other a lot and he always tells me how much he loves me, but when we see each other at school he ignores me, but he tries to get my attention or stare at me. Sometimes he can be really mean but i give it back! But he's this other person on the phone and so sweet! Also, I've seen him put on other girls "Your the best hahaha :)" (or something like that) and never puts it on my wall. But he says ily and everything like that when he texts me. People in our class think we hate each other but its opposite! Help?