The gay marriage movement started in 1989 with an article by Andrew Sullivan in The New Republic. Public opinion was decidedly against him at that time, but the movement picked up steam through Massachusetts Representative Barney Frank and a backlash against California's Proposition 22 in 2000. The state courts declared it unconstitutional and voters came back with Proposition 8. The majority of the state courts found 8 to be constitutional, but it was appealed to the Federal District Court in Northern California where Judge Vaughn Walker, who was himself gay (although he previously kept it a secret), claimed it wasn't constitutional under due process and equal protection clauses.

When challenged, the U.S. Supreme Court claimed that litigants had no standing. Governor Jerry Brown and Attorney General Harris refused to defend the proposition, something that was really without precedent. Meanwhile, other judges around the country followed suit in claiming that the anti-same sex marriage statutes were unconstitutional. Justice Kennedy of the U.S. Supreme Court, writing for the minority, said that standing should have been granted and the law allowed to stand based on the principles of federalism under the 10th Amendment. Even Andrew Sullivan agreed that voters should decided on a state-by-state basis rather than by judicial fiat. That's the history of this so far.

There will always be a dispute over this for several reasons: historically, Anglo-American laws were based on natural law and/or common law, both ultimately based on theism. Same-sex marriage is a new right that never before existed in history and is based on positive law, which in a sense declares that something is good because it is law and no deeper than that (in a sense based on circular reasoning). There's also original intent, which means when the federal constitution was written, what was the meaning of the clauses and amendments according to their authors? It does not mean that amendments are ignored or silliness like that. There are also religious differences that are significant. Liberal religious beliefs have no problem with same-sex marriage while conservative ones do. That means that it will never find acceptance among the majority of evangelical Christians, Roman Catholics, Orthodox Christians, Hasidic Jews, Muslims, Mormons, Jehovah's Witnesses, etc. Nor will it find acceptance in much of Asia, Africa and Russia. So to say, "just get over it" doesn't work and doesn't reflect the reality for most of the world.