What should I make of this.??

[Livelaughlove17]

My ex and I broke up 3 weeks ago. We broke up because he's shipping out soon and he is distancing himself from a lot of people who mean something to him so it'll be easier when he leaves. We have not spoken since the breakup (I want to wait to talk to him when I am completely over him) when we broke up he said I was a great girl and he had feelings he just felt like he should ship out single. When he talked about our breakup to my friend apparently he seemed upset; like he didn't want to do it, he just had to. He is not the type of guy to get emotional with other guys at all. He pretty much acts like I don't exist at school.. Exccept I notice that sometimes he goes out of his way to look at me when I walk by. I guess my questions are..
Why would he do that if he's the one being distant?
If I meant as much to him as it seemed like I did, why is he shutting me out completely?
Any input is welcome... Thank you!