You have two issues here.
I don't know what you said to each other in those few moments afterward. Passion makes us lose our head, but he did say he loves you and that means you have a mutual connection here. There's a big difference between a one-sided love affair and one that's returned.
There are a handful of people who lived through this kind of thing available here, but perhaps not so few living around you.
Not so long ago, my country and yours faced this every day, in every town, year after year. Men, and some women, left for Europe, maybe to the Pacific, and many never returned home. In those years it was the old, the very young, and very particularly the women who stayed at home. These people felt just like you and your boyfriend did. They were frightened of what might happen, of whom would be left behind. Time was short. Many young men, sometimes even boys, left school directly to training and within months, they were off to war.
In the stories I've heard from that time, there is one constant message that is carried home time and again: don't wait. Make the most of every moment you have together and if you feel the time is right to marry, then do it. If you see him off on a train, a ship, or a plane, then you be there. You look as hot as you can, give him a carepackage of his favorite munchies, a few letters to be opened later, and you keep your chin up with a smile inside when you talk about the things you will do when he comes home. You don't break down, you don't go through, "what if....", and you definitely don't do anything to make him regret leaving. You send him off as the hero he is and you welcome him home the same way. Only once he's out of sight, can you then you break down, scram, cry, and pray. That's what it's like to be separated by war. It's the single most difficult thing many people have had to do, but they find the strength and do it.
That's why you don't wait. You just do it. If you feel about him the way I suspect you do, then you let him know this straight away. No ceremony here, just tell him you're prepared to accept anything that happens and let him know you're not a fair weather guy. He's not alone. A soldier's first instinct is not to create new attachments when he knows he's heading for danger. He doesn't want to hurt anyone because of what may happen. Go talk to the survivors of that Greatest Generation, ask them what it's like, ask them what to do, and you'll see their faces become wistful as their memory goes back to those days and their voices become quiet. Yet I wager they will all say the same thing. If he's the man for you and he knows that too, then act now while there's time.
Of course you have to ask, "Why?"
And the replies are always the same; because those memories, the knowledge that you're home waiting for him, sending him letters, making phone and video calls, maybe sending him a pair of warm woolen socks come Christmas (it gets cold in Afghanistan!), knowing that you'll be there to welcome him home, are all the things that will keep his spirit up and his head down. To have someone special at home, not a parent, not a sister, not a mate, but someone truly special, will see him through his darkest hours. That's why you don't wait. If his only objection is to keep from potentially harming you, then he's making the wrong decision and many of the warriors who have left home for the seas, skies, and countrysides of distant lands will all tell you the same thing. Love was always the right choice.
Your job will be among the most important to any soldier in active duty though it may be the most frustrating and most daunting. You wait and do what you can to help make his life a little bit better by letting him know that your love will span to the other side of the world so that all he need do is but to think of you and you will be with him.
Sometimes love doesn't seem to be the right choice, and sometimes love doesn't have time. If you feel about each other as deeply as I suspect you do, then don't let him leave without ditching all the formality and speaking to him from the deepest corner of your heart, making sure he knows that you're committed and prepared to accept whatever happens.
Now go.