<------ Wife
These things are kind of true. It's very likely you will be gone a lot, and that you will miss a lot of your kids' growing up. Chances are good you'll miss a birth, even. At TrophyHinge's (my husband) squadron, we current have a wife who is alone in the states at her father's funeral. We have a wife who is going to shed her parasite (aka give birth) any moment now, without her husband. And another one whose husband hasn't met his 3 month old son yet. And all of us are living more than a dozen time zones from family and typical support systems. If this is what she's afraid it will be like, then she's right.
I'm probably in the minority on this, but it's not something I would try very hard to talk her into being comfortable with. If you commission/enlist and she's not really on board, life is going to seriously suck for both of you. It's hard in a relationship when you have goals or desires that conflict, especially on something where there really is no middle ground. This is one of those times. One of you is gong to have to give on this, and I think that if you have to push very hard for it to be her that caves, you are setting both of you up for disaster. I won't tell you to give you your dream of being a Marine, but at the same time, being a Marine with a depressed, pissed off, bitter, lonely wife probably isn't your dream.
Just as being in the military is not a life for everyone, being a military spouse is not for everyone, and it isn't something everyone can handle. Since you picked the wife first, it seems like that's the circumstance you have to work around. If you'd joined the Marines first, then you'd need to pick a wife that could handle that choice of career, but since you picked the wife first, you need to pick a career than works with your choice of spouse.
Some women handle it just fine. I'd like to think I'm one of them. My husband is deployed and yet last night I went out with JOPA and got sloppy drunk and did kareoke. For me, when he's gone, life goes on. When my car won't start, I sort it out. When there are family issues (mine or his), I sort them out. When I'm not with my family at Christmas, I suck it up, and when my husband is gone for my birthday or anniversary, I find something else to do to pass that day. And I'm not unique; I don't say this to toot my own horn. I say this to let you know that people who can do this kind of thing tend to make successful, not-miserable military spouses. Those who need their husband to call twice a day to check in, those who freak when the refrigerator breaks and let him handle it because that's man's territory and they wouldn't know where to begin, those who need input on all major decisions before they feel comfortable making a choice, those who have even the slightest edge of neediness, those who need firm plans and don't do well with improvisation, and those who can't accept that they might not know where they are going to be living in 3 months are going to struggle, a lot, which means their husband is going to suffer a lot as well. So you need to take an honest look at your wife and decide which category she falls into, before you continue trying to get her to accept this choice,
I'm not suggesting that you give up entirely, but if she's really dead set against it, you are in for a lot of misery if you do it anyway, or if you talk her into saying she's okay with it, when she really isn't.
All that being said, if it is just a case of her not understanding, or wanting more info about how it works or what it's like, if you want, I'd be happy to chat with her and answer what I can. PM me. My husband is in the Navy, but in most ways it is the same animal from a spouse perspective.
Great job, Villanelle!