I wouldn't even make an exception for your kids, because if you aren't taking care of yourself then you can't take care of anyone else to the best of your ability. When parents push themselves beyond their limits for an extended amount of time, their mental health eventually suffers, and that can have drastic consequences on the very children you're trying to protect.
It's like they say on airplanes-- if there's an emergency, you put your own oxygen mask on first
. Your kids can't help you with yours if you're unconscious, but if you've got yours on then you're in a position to help them.
On the initial question:
My requirement is the same in all of my relationships: that we pursue the kind of relationship that makes the most sense for the two of us. Usually that involves finding a way to spend time together (anything from phone dates to living together) and working together on common interests (which might well include those big scary projects like raising a family and paying rent, or maybe just swapping bad scifi novels).
At the end of the day, what really matters to me is that we both want to be in the predicament we've created.