Did anyone think the assault on marriage would stop once gay marriage became legal (and continues to become legal). Of course not! And that is exactly what is happening. Polyamorists (the belief in group marriage–i.e. a marriage consisting of more than two people) are clamoring for their rights, too.
And to be consistent, one who believes in gay marriage would also have to support other types of marriage that are not traditional like polyamory.
Citizen Link by Focus on the Family has an article detailing this trend. And it won’t be stop there. Pedophilia, bestiality, and other forms will all have supporters arguing they have the fundamental “right” to marriage.