Hi Never-Ending ^_^
There's a lot of courage in you and I'm glad that courage lead you to posting here.
I think what he is experiencing is a bit of army fever, and I call it that even though it's similar to any circumstance where you may be taken away from your day to day life. He has probably spent some time thinking about how his life was and it's common to think of the different ways it could go.
It's flattering that he is thinking of you but what he's doing the most is thinking about things that are different than the army.
There is nothing to say that he isn't genuine about what he would like but the obvious advice is to make sure he has time to get to know you first, he might find over time some personal things which he himself can't overcome though obviously you've made a good impression on him already ^_^
I think the real question is what would you like?
There are a few sides to this and one of them is the christian side asking what the right thing to do is and I think again that speaks a good volume about how much the lord means to you. The religious side and the personal side (and the social side etc.) will always wrestle with each other as to what each one wants but for advice to the personal side (the part that is still attracted to him) I suggest putting some breaks on him and let him know marriage is a serious thing to you and it means a lot personally. The reason why I suggest this is so that you can give him time to re-adjust himself after the military life should the two of you decide to continue with a relationship, give him time to re-adjust that dream of his as well (which is where getting to know you and you getting to know him come into it).
You also asked why you yourself are attracted to him and that's probably the hardest personal question to ask but the easiest one to get confused with the answer, the time you spent together I'm betting you felt loved and that beyond all else is a wonderful thing. It's not a sin to enjoy love, loving or being loved yourself. But be careful because to truly love some one is to know them and to love everything about them, a child can love a toy 100% before they actually have it and play with it but it was not the toy they loved 100% it was the idea and thought of playing with it (I bet that just explained a lot to people with children or even explained our own childhood a bunch
).
For the religious side I would let every one elses posts be the final word but I want to explain one thing, beyond all else god is love and Jesus told us to do just one thing and that was to love as he did, it was a moment where you didn't love the other person above yourself because as you said you didn't do it with the intentions of it lasting.
No one should love you less or judge you in the least for doing it but you have to understand why it was wrong in order for you to understand what you are asking to be forgiven for, if you don't decide to pursue a relationship with him that is entirely the thing you will be asking him to forgive you for ^_^
Be warm with love and always consider others
<3
Rob