So there are major differences in how civil and religious laws treat marriage and divorce. That brings us back to the topic of gay marriage. This kind of disparity already exists in other areas, so the principle is not at issue. What is at issue is the specific idea of gay marriages. And at the root of this is the very idea of marriage.
Marriage is more than just having kids and raising a family.
This Darwinian view of marriage focusses on ensuring the success of the next generation. There is more to it than that. Many marriages are childless. Many marriages have kids but then the kids move out, leaving the parents as empty nesters. A spouse may die, and the remaining spouse may remarry.