We all know that far too many marriages end in divorce, yet the institution does not adapt. Indeed, most Americans today want to expand conventional marriage to include same-sex couples.

So why is there no effort to improve the legal structure of marriage, when it shows itself to be deficient?

Marriage is a legal partnership that lasts a lifetime — one lifetime to be exact, that of the first of the spouses to die. Generally speaking, that is a long time for any partnership. People, circumstances and all sorts of other things change. The compatibility of any two people over decades may decline with these changes to the point of extinction.