As an idea --quite separate from people-- same-sex marriage is a failure of imagination and creativity. Ironic, from a group --well, the men, at least-- who are supposedly renowned for their fertile imaginations and creativity.
Marriage is a heterosexual structure, inherently. (And weddings are a female ceremony, really*.) Were it not for the connection between male-female sex and child-bearing/child-rearing, it would never have existed. Marriage requires at least one of each of the following: a husband and a wife.
A man can't be a wife. Any more than he can be a mother.
It's a structure set up for another kind of dyad, not the kind that happens between two men. Aside from all the societal problems involved in emptying and recreating marriage as a genderless contract, it does not honor love between men. Which has its own archetypal shapes and structures and which, if gay men were imaginative and creative, they could use to create structures and rites that actually fit their own reality.
I have experienced the kind of love that makes you want to form a unique and permanent bond with another man. A combination of friendship, desire and kinship for which I cannot find a simple name. But "husband" is not it.
I even find myself thinking that the push for gay marriage is an expression of internalized homophobia. Rather than thinking themselves good enough to create their own forms of relationship, gays are now dogmatically convinced that they have to find validation in one that is the consummate straight institution. As if the only way they can say that they are good enough is to ape what male-female couples do. A merely convenient and anxious (and vengeful) way of trying to prove, pointlessly, that in their dyads they are not that double header of egalitarian shame: separate but equal second class citizens..
Gay marriage enacts one of the worst traits of gay culture: making decoration rather than art. Rather than being really creative, it's just an ornamental rehab of a house someone else designed and built for another purpose. It's derivative of and parasitic on something straight. An imitation.
For homoerotics, getting married is donning straight drag.
*When nuns --in the Latin West, anyway-- make their vows, their female souls need to include a bridal element in it. Monks don't.
And weddings these days. Insane. While women deafeningly assert their equality, their increasingly bizarre and expensive wedding ceremonies trumpet the ineradicable difference between males and females. And ever more extravagantly unite them in a contract which they can ever more easily walk away from. And do.