[throwaway4aday]

If the earner dies: life insurance

If the earner leaves: alimony

It's not like we haven't solved these problems before. Yes, we could improve legislation around this but the basic idea is that if you have a contract with a partner where one of you earns the income and the other does the work at home then part of that contract is to recompense the person who is not working if the one who is fails to live up to their side of the bargain for whatever reason.