He wants to join the military

it's been 2 years since we've met, and in this long distance relationship. Hes 18 and I'm turning. I move to closer to him and school in 9 months, and he's telling me he wants to join the forces to keep me and his family and country safe. He wants it to be OUR decision if he goes, but I don't want him to if we're closing this gap soon after going on 2 1/2 years. What should I do? Let him go? I need advice.