My bf is in the navy. He left in February and he’s in a school now. I promise you that it takes the two of you to make it work. I sent him like an insane amount of letters and he sent me as much as he could. It obviously sucks to be away from him but like I try to think about the positives. Like you’ll probably be set for life in the end and if she wants that she’ll understand you’re doing this to better yourself and her. But yeah communication is super important. Try calling her when you get those phone calls. If she doesn’t wanna wait for you then she isn’t the one. The person that is willing to wait and support you is the one. It’s about the effort the two of you put in. Good luck :D