That is the exhausted state of all mothers of young children. That's usually only a few years, at the beginning of the marriage. And that is the length of time that almost all marriages last.

Women either need to have more children (to extend this phase and to be "allowed" to remain home), be housewives (to increase their leisure time), or the husbands need to do A LOT more childcare and housework, to make the cost/benefit analysis of continuing the marriage more attractive.