Nate Silver ran the numbers on divorces and states that have gay marriage bans. Those bans aren’t good for hetero marriages:
Over the past decade or so, divorce has gradually become more uncommon in the United States. Since 2003, however, the decline in divorce rates has been largely confined to states which have not passed a state constitutional ban on gay marriage. These states saw their divorce rates decrease by an average of 8 percent between 2003 and 2008. States which had passed a same-sex marriage ban as of January 1, 2008, however, saw their divorce rates rise by about 1 percent over the same period.
Check out his post with the chart of the states. It’s telling. My non-scientific conclusion is that same-sex marriage actually strengthens the institution of marriage.
So, states that want to protect marriage should end their bans on same-sex marriage. But, that won’t happen. We’ve already seen one theocratic Republican, Sally Kern from Oklahoma, introduce legislation to make some divorces illegal.