A different group has sided against gay marriage before the Supreme Court: gay men who are married to women. This is not at all unusual, that homosexual individuals enter into a marriage contract with heterosexuals, and in fact it’s actually what the right-wing wants to promote, by compelling people to only have heterosexual relationships. As is always the case when one group wants to deny rights to another, though, their arguments are sad and petty. The gay-men-married-to-straight-women have to actually argue that allowing gay-men-married-to-gay-men would somehow mean their relationships would be excluded. It always boils down to some group claiming that removing a restriction from another group is exactly the same as adding constraints on them.