Without defining "works hard", I have to generalize. But the traditional role of father/husband is to work to provide while the role of the mother/wife is to care and nurture for the children and home. Women, generally, have traits which are better suited for that role. Generally. And it's by far one of the most important and underrated roles in human civilization: raising and caring for the next generation.
That said, this doesn't account for single mothers or fathers who justify being absent from family responsibilities by "working hard."