Why do we even have spousal support in Virginia?

Professor of Law David D. Friedman highlights one good reason using explicit economic theory: 

Two firms agree on a long-term joint project.  One will research and design a new product; the other will produce and market it.  The first, having done its part of the job, hands over the designs – and, in a world without enforceable contracts, the second firm dissolves the agreement, produces and markets the product, and keeps the money.  This is the problem of opportunistic breach . . .

A couple marries.  For the next fifteen years the wife is bearing and rearing children – a more than full-time job, as those who have tried it can attest.  The husband supports the couple, but not very well, since he is in the early stages of his career.

Finally the children are old enough to be only a part-time job, and the wife can start living the life of leisure that she has earned.  The husband gets promoted to vice-president.  He divorces his wife and marries a younger woman . . .

In a traditional marriage the wife performs her part of the joint project early, the husband late.  That timing, combined with easy divorce, creates the potential for opportunistic breach –   encouraged by the fact that most men find women more attractive at twenty-five than at forty . . .

One of his proposed solutions to opportunistic breach in marriages is one that we all know about: imposing substantial damage payments on the breaching spouse (e.g., spousal support).  David D. Friedman, Law’s Order (Princeton University Press 2000) at 174.