This is no easy question. The basic problem is that a marriage is an economic machine that churns out value. It churns out savings on day care, savings on housing expenses, savings on recreation. It churns out educational progress---children of married couples, even when all else, including IQ, has been held constant, do considerably better in school.
If the marriage breaks up, this stream of wealth and value is shattered. How can the damage possibly spare the stay-at-home Moms? We do have some paltry protections...community property law, social security benefits for divorced wives, child support payments, AFDC, earned income tax credit, etc. etc. The mother will not be left penniless. The guy won't go to debtor's prison. But that's it.