Molly Ball’s excellent article in The Atlantic traces the development of the ongoing campaign for marriage equality. Ball notes that 2012 was a watershed for the gay rights movement; after losing in state referenda 31 times, advocates of gay marriage were on the winning side four times (Maine, Maryland, Washington, and Minnesota). More Americans now support same sex marriage than oppose it, and the margin among younger people is growing wider.
As the chart shows (from Freedom to Marry), marriage isn’t available to same sex couples in most of the United States, but the progress over the past few years has been extraordinary. The Supreme Court has taken two cases on same sex marriage this year, and Republicans are debating how much value the strong anti-marriage position in its national platform provides at the polls.
The world is changing and these changes don’t happen by themselves. Tracing the routes to influence for social movements makes for a complicated tale with many important factors, including celebrity endorsements, cultural products like the tv shows, Ellen, Queer Eye for the Straight Guy, and Ellen, and the strategy of coming out.
Ball’s tale puts activist lawyer, Evan Wolfson, at the center of the story; it’s a 
good choice and a compelling case. A veteran of the Peace Corps, and a former prosecutor, Wolfson has been focused on marriage equality for more than three decades. Ball reports that he wrote his last student paper at Harvard Law School on the topic.
Wolfson founded Freedom to Marry in 2003, and has spent the years speaking at rallies and conferences, running his organization, talking to the media, briefing politicians, arguing cases, raising money, drafting legal briefs, writing for a popular audience, and meeting with other activists to argue about priorities. His name doesn’t come up in most reports on referenda, court decisions, public opinion, or the evolution of individual politicians like Joe Biden or Barack Obama, but Ball sees his fingerprints everywhere, in the arguments, images, and events that led up to November 2012.
For Wolfson, the struggle continues. As a lawyer, he wants to see recognition of the right to marry from the Supreme Court. As a civil rights activist, he is dubious about subjecting basic rights to the vicissitudes of the popular vote. Ironically, the larger movement’s successes with public opinion make such a judicial outcome more likely.
Politics Outdoors 
I would add to Wolfson’s accomplishments a rather tireless engagement with fellow LGBTQ activists who were not only uninterested in, but strongly opposed to the fight for marriage equality, on the basis of a critique of the institution of marriage, as well as creating another category by which some of their community could become included in mainstream institutions and others left out. Many of the conferences Wolfson attended set him up as one half of a debate on the question of whether marriage should be pursued at all.
Of course, you’re right. These kinds of arguments are constant within social movements; it’s one of the reasons activists rarely feel that they really won. There’s also an interesting irony, constantly recited by activists, that the most visible achievements of the LGBTQ movement have been access to marriage and the military, two institutions many never wanted to enter.