It would seem to me that redefining marriage would not have been in the minds of those writing the constitution, so it would not have been addressed. They were going by Biblical Christian principals, or at least Godly principals, at that time. The intent of marriage has long been between a man and a woman, even by atheists! Most sensible people will agree that a child needs a father and a mother in order to grow up a well balanced person. In those cases where one parent is left to raise the child alone, it is difficult for that parent, but being the resilient people we are, we do our best for our children.