What should I do? Is he cheating?

I think my boyfriend is cheating/ planning to cheat on me. We have been dating for 5 months now, and i thought it was going pretty well. We haven't had any fights or anything. Im joining the army and leave for boot camp in three weeks. So the other day my best friend comes up to me and tells me that her cousin told her that he told her "hey, after Julia leaves you should come over so i can have a cuddle buddy" And it seriously hurt me to hear that, I trust him..kinda. Because I can totally see it happening (he has had a lot of ex's but never heard if he's cheated) but then also the girl is known for causing drama. I asked him the other day if he was going to write me (that's the only communication you can have) and he said maybe. But its wasn't the cutesy joking maybe it was kind of a serious with a joking undertone maybe. And i was trying to get on his fb when a bunch of us were together and he wouldn't let me, but the second the "other girl" wanted to get on he let her. It hurts more because we discussed this being a serious relationship. I don't know what to do or think. Ive never been cheated on before, but at the same time i don't know if he is or not. What should I do?





EDIT: he also plans to join the army. I enlisted before we were even dating.What should I do? Is he cheating?
I honesty think that he does have interest in another girl, but that doesn't necessarily mean he's going to cheat. I don't know him, so I can't judge them. Talk to him about it.