How do I get him to like me?

So I've had a crush on this guy, Blake, for quite some time now. I liked him in 8th grade, then my freshman year, we didn't have any classes together, so we didn't talk much. Now we have 2 and we talk so much that BOTHA teachers moved him away from me. So now we text and Snapchat, but we don't even talk outside of school. He always tells people that I'm his girlfriend, but I know he's kidding. I blush so bad when we talk and I get butterflies when we walk together in the hallway, but why doesn't he talk o me outside of school? He tells me I'm beautiful and that I look good almost everyday, but I don't understand his behavior... Advice?