The fundamental question is whether the primary unit of the society is a household or an individual. If you assume that the society consists of individuals, people should be taxed individually, spouses should be allowed to choose in advance how their assets would be divided in a divorce, and alimony should only be paid to support underage children.
I think the currently prevailing view is that a household (or a family) is the smallest social structure and the individual is pretty much the opposite of society.
Exactly. Economists usually regard households as basic economic units for good reason.