Why am i awkward with him?

First of all, we were best friends, then we fell in love with each other. We don't see each other in school because we're in different classes and things. But we talk on facebook ALL THE TIME. he says how we're defiantly going to go out. and how he wants to kiss me in the rain and everything, all on facebook! and texts, and also we write letters to each other. But for some reason, we're awkward when we see each other in school? we hardly do see each other, but for some reason, it's just awkward :S how can we make the awkwardness go away? i really like him.