I'm a father of two, 9yo and 6yo. My s/o and I both have this problem, and from what we've experienced, and keep in mind, just our experience, we just want to hang out with each other. Working all day, taking care of the kids all day+all the housework, it's lame. And when I get home from work, we just want to lay up and watch some shows, make sure kids are fed, homeworks done etc... Then re-gear to do it all again tomorrow. Parenting, whether you stay at home or be the breadwinner, is pretty tireless. However you can work out a routine, divide labor, and find your balance is going to be what it's going to be.