Aka: The more I'm away from you, the more I like being with you.
I wouldn't focus on explaining what makes you happy if you want this conversation to end well.
If nothing else, it's a good way to test how healthy your relationship is. I already knew the answer before I joined a startup. We were watching Devil Wears Prada and she quipped how whiney the main character's boyfriend was about her career. Relationships really are better when you're doing what you both enjoy. She may not have enjoyed her job, but it set her on the path to the job she wanted.
Now excuse me while I punch myself in the nuts for knowing so much about a chick flick.
For double effect tell your spouse "There's more to our relationship than the quantity of time we spend together. A job that makes me happy increases the quality of our time when we are together."