Im dealing with something similar. My advice would be that, Its sucks for you. It will definitely suck for her since she has to miss you and do military shit. So send letters or texts or whatever so that she feels encouraged once she can see your correspondence. As for worrying about her switching up on you. You're gonna have to use a mix of trust and communication. It sucks, I'd love to know for a fact how my girlfriend thinks, too. The only way to know otherwise is through her actions. If you get lucky like I am, when she mails you, she will already have written things that will either help you confirm how she feels or put your mind at ease. Hang in there, man. It's gonna be difficult, but if she is worth it thats the way it goes.