Don't know what to do?

So I've (M/16) been messaging this guy (M/16) on snapchat who i really find attractive (he's from the US and I the UK). We've exchanged "pics" now and again but im not just interested in that, I like him. We've talked quite a lot but we never really talk about our 'relationship' since we are both in the closet and are usually speaking in a party of straight friends.The thing is everytime i message him saying hey he responds asking for a "pic." I always wanna talk or flirt with him but he just wants to trade pics. I really like him when he does talk to me but nowadays that is rare.So I'm not sure what to do. Should i cut him off because he doesnt like me and is using me? Or is our long distance relationship just not gonna work? I really dont know and need some advice. Anything...