When my wife and I first started dating, I started teaching her some basics of self-defense. Shortly after we were married and we were looking for ways to pay for me to go through law school, she suggested that I open up my own martial arts school (I was by then a 4th dan and had run a branch location for my instructor back in California prior to moving out here to continue my education), since it would not be time consuming (LOL), and she could help me run the business end of it after she got off work.
Well, now it's nearly 15 years later and I never made it to law school, though I have no regrets about that (though she does bring it up every now and then, especially when the parents get too out of hand). My wife and I make a comparable living to what I would have made if I went that route, but now she works at our school full time. She just earned her 4th dan this past summer. She teaches four martial arts classes per week, plus the fitness kickboxing, tai chi and yoga classes. We are also seriously looking at her managing this location and me opening a second one.
As far as our training together; she still will often train when I'm teaching a black belt class, but she and I learned a LONG time ago that we don't partner up together. One of my other senior bb's (also 4th dan) has been her training partner for many years. It's kind of funny actually, if I need to make a correction on something she's doing, I can say "Allen, tell her to bridge a little more on that armbar" or "pivot more on her round kick" and she will act like she didn't hear a thing. Then he'll say "Sandy, you'll get it better by bridging more on the armbar and make sure to keep your knees tight"; and she'll do it no questions asked. And all is well in the universe when I get home. But heaven help me if I forget and say it directly to her in class. She may not say anything to me on the floor, but wait until I get home. Yikes. It just goes to show you, no matter what your rank or how many championships you've won; if you are married, there is always a higher power.