Relationship advice?

De
So I have nobody I can really turn to and ask for advice on this. My boyfriend of 2 months (on the 13th) keeps bring up Everytime he's alone and thinking about how he's leaving Ga in about 2 1/2 years (he's a marine). And it always ends up with me in tears and beyond upset because he doesn't want to get married but won't take me with him due to the fact that my mom said he had to marry me to do so. But in the next sentence he goes on about how if he ever gets married and ever has kids this is how he would like things to happen. I honestly don't know what to do. We had one of those conversations last night and I ended up in tears and so upset that my chest started to hurt. I don't want to loose him and he makes me truely happy when I am with him and even when I am talking to him. I just honestly don't know what to do anymore. He doesn't want to hurt me in the long run so he's pushing me away and keeping me at a distance. Any advice would be great. Thank you in advance.