Well, because we're so different as people. And it's that difference that probably also makes it easy to stay together, because we don't get in each others way.
The only job I'd ever had that might be considered not playing music was teaching guitar, which I did in college for a while, but that still falls in the same category.
In our relationship, we don't have that situation. I don't require what he needs, and he doesn't require what I need. I know what I do; I have an amazing life that nobody knows about.
There's always a personal satisfaction in writing a song by yourself. You get the inspiration, and see it through, and you're done. It's focused and very personal.
Once you've made a record, you don't need to make it again. It's done, and it's out there forever, a moment in time that encapsulates whatever was happening in that moment.