• They confused their own beliefs with those of mainstream Republicans, who were far less ideological and, in fact, were following the societal shift.
• They did not drum out of their ranks anti-gay (as opposed to pro-traditional marriage) voices, who portrayed the entire movement as intolerant and exclusionary.
• They had no logical objection to states' popular referendums in favor of gay marriage. Instead they were reduced to making an anti-democratic argument that voters couldn't or shouldn't be allowed to define marriage as they saw fit.
• They ignored the plight of heterosexual marriage (soaring divorce rate, rise in single-person households), which made their defense of "traditional" marriage seem insincere.
• As more gay and lesbian Americans came out to friends, family and co-workers, the anti-gay-marriage voices were handicapped; they argued against an issue in the abstract while gay-marriage proponents could argue that Sue and Ann at the office shouldn't be denied the right to marry.
• They insisted on federalizing the issue with the Defense of Marriage Act, turning federalism into an argument about federal meddling into marriage.
Living in a political bubble of right-wing media, in which everyone agrees with certain nostrums, leaves the right vulnerable to shifts in opinion and outmaneuvered when new, persuasive voices enter the fray.
Conservatives should take this as a lesson and a warning and not just on social issues.