My brother is in the army. It takes a strong, courageous and pretty damn tough woman to cope with it. And she does, she does it so well.
The army isn't all doom and gloom.
But at the end of the day its his life and if he values his career (not job) more than your relationship surely that should be telling you something. It's not your choice and sad though it is maybe you're not made for each other if you can't stand by him through it.