Part of the blame goes to the majority of voters, who simply lacked sufficient compassion to recognize justice when it was right in front of them.
Much blame goes to the California Supreme Court. That court struck down a state ban on same-sex marriage in a 4-3 decision in May, spurring the Proposition 8 campaign. Why don’t State Supreme Courts notice that federal courts, already burned by Roe v. Wade, leave gay marriage alone? The State courts keep treating this issue as purely a legal one without considering what we in the law call prudential matters—are people ready for it? Will the legal arguments be persuasive? What will happen next? Even the terms of court decisions make a big difference. A court can strike down a statutory ban on gay marriage but leave the decision in abeyance until the legislature can deal with it, leaving open all kinds of compromises, such as civil unions, differing terminology etc. Justice Scalia once said that Roe did not really aid abortion rights in the long run because it nationalized what had been building state by state compromises on abortion and created the pro-life movement. Courts are better threats than actors and judges should remember that.