too soon?

My bf and I are long distance. he gets out of the army in 3 years. we have known each other for years but only been dating a couples months. we've only seen each other 4 days out of these 2 months. he is a hopeless romantic and tells me he wants to marry me so I can move with him so we can be together. he knows it's really soon but he says he can't imagine a future without me. I feel the same way but I think more logically. I can't drop everything and move 3,000 miles away. as much as I would want to. I want to be with him so bad and I miss him so much. I don't really have anyone to talk to about this. any advice?