For centuries composers have used the theme and variations form to organize musical thoughts and express them in contrasting settings. Good variations derive from clever artistic and imaginative manipulation of the elements of the theme. The variations may be interesting and compelling, but they can never be the theme. A variation cannot usurp the place of the theme, because it was derived from the theme. In a good theme and variations there cannot be just one variation, otherwise it would be set at competition with the theme and could even claim to be the theme.
Same sex marriage by definition has components that derive and deviate from the historic theme of marriage, but no matter how it is manipulated, it can never be marriage, only a variation of it. As a composer of a good musical theme creates interesting variations, so marriage has some intriguing possibilities of variation. Time will tell which variations get accepted by the publisher and are judged worthy of a performance. I wonder what the criteria for their selection might be?