What about couples sixty-five and older? Should they be prevented from marrying? I've never heard of a pregnant eighty year old (not counting Sarah in the Bible, who had divine intervention), so maybe it's true that they CAN NEVER EVER have children either.
They didn't start out old remember. That's an invalid argument. They are usually parents and grandparents and great grandparents by then. So it is a natural family arrangement, even if that specific couple married late. We are talking about the legitimate practice of protecting a unique relationship -- that of male/female marriage. It is nature's definition of family whether you believe in God or not.
My baby is off to college in the Fall. I think marriages should automatically dissolve when the children leave the nest. (at least that's how I feel today...grumble, grumble)
Of course there would be the renewal option if one was so inclined.