As far as I've experienced a guy gets interested in a girl if she let's him chase her so you'll have to tone down your level of interest to a minimum and act really cool, not get emotional, not talk too much and not explain everything you do. Pretty much you have to hold off your interest and pretend to be carefree. Don't try to make him jealous though talking about all the men that might hit on you.
You can tease him a little. You don't have to be serious, in fact it did you a huge favor if you'd started being playful and hard to guess from time to time. You should end convo first most of the time so he'd feel repelled to wonder what you're doing.
The way you get a man to chase you is when you spark his interest and men love a challenge, I think since he's in a military, he would appreciate it even more. You need to be a bit more secretive and not so forward talking, you know. Purr, don't meow all the time.
You have to be feminine, I don't know if you are or not, but upgrade that.
Next thing you need to not care so much about him, be like you don't mind his company but not overly eager.
Never invest more time or effort into a relationship than the man you're dating (you guys are sort of dating so that's why I say that). Right now you're doing MOST of the work and he's complaining because there's virtually no challenge, and he hasn't really done anything to deserve your attention like that.
The man is telling you that you need to make a huge change that is visible to his eye and mind, if you're ever to stand a chance being his gf. So that's what you'll need to do-do the opposite you've been doing and let him watch it. You don't have to change your moral value system or your entire personality, he likes that about you, you just need to make a few adjustments to your approach to him, that's what he's talking about.