MY FINAL OBSERVATION IS THIS: Lawyers, legislators, judges and policy analysts cope continuously with complexity. If they take a step back and look at the requirements to marry and to remain married, they see that the law and structure of marriage is so minimal, so simple. It is an example of what mathematicians call elegance — like Einstein’s equation E = mc2:
One man — one woman — indivisible.
As the poet Keats wrote in his “Ode on a Grecian Urn”: “Beauty is truth, truth beauty.”
(1)Sexual relations between a man and and a woman are the ONLY kind of sexual relations which can spontaneously give rise to the existence of another human being. Securing that child's rights to the support and nurture of both his natural parents --- father and mother --- which is the essential public purpose of legal marriage.
(2) Although there are man/woman couples who are either unable or unwilling to have children, it goes beyond the scope of government of surveill their marital relations and/or their medical records to determine whether they do or don't intend to remain childless.
(3) Therefore the state, to secure a child's natural rights without invading the marital privacy of the couple, simply assumes that every man/woman sexual alliance is potentially procreative, and thus is eligible for such measures as the state may take to augment its stability.
(4) Why wouldn't this be convincing? It's been convincing for 3-4,000 years. It's not perfect--- not by a long shot --- but man/woman marriage does involve a public interest that flows from its one unique characteristic: fertility.
Why would the state want to license love and affection? ~We're~ interested in love and affection, but the state's interest isn't romance: it's in the protection of the procreative unit, and securing the rights --- very much including the property/economic rights ---of the progeny.