While I’m on the side of this doesn’t really matter why, and you are writing about your niece’s feelings I still want to give a “what if,” even though we really don’t know why. This young man might be scared of being deployed. He might know how hard it is going to be to focus on what he is doing and trying to keep up a relationship and is afraid he won’t have the mental capacity to do so. Dealing with a loved one overseas is hard. Wondering how they are doing, what they are doing, etc. Maybe he was trying to save future heartache for the both of them. No contact might be better since he’ll be overseas and won’t know when he can contact her.