One reason Americans have moved so rapidly toward support of same-sex marriage is their stubborn bias toward liberty. When interest groups demand something material, or when they seek to take something from other groups, the public is apt to resist. But when a group asks to live and let live, it can usually count on getting its way.
The right to marry a person of the same sex fits perfectly within Thomas Jefferson's conception of freedom. "It does me no injury for my neighbor to say there are twenty gods or no God," he wrote. "It neither picks my pocket nor breaks my leg."
The beauty of gay marriage is that it grants something to one group that doesn't come at the expense of anyone else. Heterosexual rights are undisturbed. Straight people could marry before any state legalized same-sex matrimony, and likewise after.
It's a bit rich for these groups to complain that the court is infringing on their freedom to infringe on the freedom of gays. Advocates of same-sex marriage are not trying to exclude heterosexuals from matrimony. They are only asking to be free to practice it, as well.
The only liberty they will lose is the liberty to deprive others of their liberty. Sorry, but that's one freedom a free society doesn't offer.