Well, most wives are also mothers and their husbands are fathers. We're all run ragged and broke. 😂
And, after the kids are grown, you don't change because you've been like that for decades. Besides, kids are never really "done" and grandkids eventually show up.

Romance is a rather modern idea, really, resulting from being wealthy and having hired staff. Someone with 8 kids and a potato farm isn't thinking about romance. They're just happy to have enough to eat, and they just sit on their porch and look at their farm.