Hey Brother,
I'm a SSgt in the US Air Force.
The Air Force doesn't focus as much on holding back emotion or focusing on military bearing, it's a lot more relaxed for us. But I am fully aware of the training in military bearing you are referring to. So I know where you are coming from.
You couldn't be more correct about people respecting and admiring that bearing. It's a very dominant, manly way to present yourself. And women do appreciate that sort of man, usually.
So for approaching women, your bearing will work to a point, but I'm sorry to say you're going to have to drop it down a notch at some point during the interaction. The military bearing, especially that of Marines, is great to show you are a leader, a successful man. But it can very easily make you come off as an "asshole" (not in a good way). Ask any female who's dealt with Marines, and a lot of them will often say they're assholes. I know better, I understand the mentality, but their perception is often thinking that Marines in general are just dicks.
Is there a time and a place? Yes of course. You can still keep your bearing while smiling and showing some teeth. If I were you, I'd let the walls down some when interacting with women so they don't take you as being a dick.
Now here's something I've dealt with time and time again. You are going to be stationed in a military town, obviously. Believe me when I tell you, women in military towns are generally very jaded from military men. Not all of them are, but you'll definitely find some resistance. I suggest when you're in civilian clothes, you try to confuse the women on whether or not you're a Marine. Example: If you get a few days off, don't shave. If you take a month of leave, grow a bear and let your hair get a little longer. Don't tuck in your shirt. Keep the bumper stickers off your vehicle. Don't get visible military tattoos, etc. When women ask you what you do for a living, tell them you're a belly button lint salesman or something.
When it comes time for a woman to know what you do for a living, you tell her "I'm in the Marines," not "I'm a MaRINE!" (I know how you Marines like to emphasize on RINE

). When you get on the subject of how much you like your job, etc, don't go into any "I love my country" stuff; they've heard that time and time again. Me, personally, when I meet a girl who is suspicious of my military career, I give her the following: "I really love my job. I mean the military isn't for everyone you know? But oddly enough, it's for me. It's just something I'm good at. And I love it."
All I'm saying is to definitely set yourself apart from your competition. The girls are used to military guys flaunting their uniforms, acting super-dominant, trying to get girls with that basis. Present yourself as who you are, drop the bearing a little bit at a time, and stand out. The girl will respect the fact that you have a solid career once she understands you're not a total dickhead.
Also, you're going to be an officer, and you know as well as I do that you'll have quite a few Marines under you. When telling a girl about your career, avoid using terms like Platoon, Company, Squad, etc. Instead, talk about how you have 50 guys under you, not 50 Marines. When talking to girls, it's not a Platoon, it's your organization. Never tell a girl you're on base/post, tell her you're at work. When sending selfies, send them in civilian clothes. Only after a bit of rapport can you send them in your uniform. Even for me, when I send the selfie of me in a uniform, sometimes the girls say "Oh. I didn't know you were Air Force..."
And of course some girls just love the uniform. One girl I've been hanging around lately, she told me very quickly she thought my uniform was sexy. Some girls just dig the military still; but it's not as many as you think.