What comes after Gay marriage? No fault adultery.

Everyone who was opposed to Gay marriage argued the 'slippery' slope - allow gays to marry and then before long you'll be marrying polygamists, etc.  But Polyandry and Polygamy aren't big in the west so it is unlikely that they'll every make a big issue one way or t'other.  There are peckerwood Mormons who keep doing it in defiance of the law and our attitude aside from the occasional racy miniseries is live and let live.

But the one thing that has never been acceptable in mainstream marriage has been adultery.  Yes, it's honored more in the breach than in the observance but there has always been a moral standard and everyone knows what it is:  sexual fidelity to your spouse.  And this applies to gays as well as straights.  But I can't see how the morality of the adultery ban survives gay marriage.  And the problem as always is men:  we men don't like to limit our sexual roaming.  We get it limited for us by the peculiar biology and social power of women.  Shorn of that constraint the average man behaves in a much more promiscuous manner - whether its on shore leave in Subic bay or Friday night on Castro street.  And there are more and more marriages that are between men, meaning more and more high testosterone libidos rolling around inside of them.  And if we know anything about how Gay America approaches these issues, they will demand 'equality' which means they will demand a lessening of the moral and legal stigma of adultery - in the culture and in the courts.  And the GLBT movement, currently in its existentially greedy phase, will demand that the new rules apply to everyone, that there not be a gay 'ghetto'.  But even if they don't get a dejure change, the defacto change in mores among a social and artistic avant garde will shift public opinion further away from strict monogamy than it already has moved.  In the end we'll neither have marriage nor fidelity.  Just useless, broken down clapped out institutions that used to mean something but now have lost their point.

But that's what happens when you screw with the social foundations of a society.  Conservatism includes the root conserve for a reason.  It is very hard to 'make the world anew' without hurting a very large number of real people.  Even if doing so makes you feel good and hip and all.