And "war is bad" and "we need the rest of the world's friendship" and all the other clptrap.
Marriage is about creating a stable base for procreation. The nuclear family unit has been proven over millenia to be the optimal way to do this which is in the best interest of society. Easy divorce or childless couples does NOT undermine this premise, anymore than driving your passenger car on the Interstate system designed to allow military to move quickly undermines that effort.
Why two? Whenevr I ask that question, I can never get a straight answer. If ANY part of marriage is up for grabs, then ALL parts are. Why two? Why the same species?
The bottom line is that if marriage is not ESSENTIALLY AND INTRINSICALLY about bringing up kids, then it has NO MEANING AT ALL.
Which is, of course, what the Isamifacists and the rest of the America-haters want. Remove the fabric of society and the whole thing unravels. All morals are relative.
If that is the case, then it has no meaning at all. I always thought it was about devotion to one's spouse - regardless of whether they choose to have children or not, or even to adopt.