Boyfriend and the military?

My boyfriend and I have been together for almost 4 years now. He recently joined the military. Now, he is talking about how he wants to just focus on basic and then go to AIT. He says he doesn't want to have to worry about a girlfriend he just wants to focus on his career. He says" If it is meant to be it will be". I have also noticed that he has been somewhat pushing me away. I have to coax him into telling me I love you, when it used to be given freely. I am hurting, but he doesn't seem to realize it. Should I just let him go? I don't know if I can. I'm worried and on the brink of a total emotional meltdown. I need some opinions. Please.