Peter Suderman has a compelling post on the evolution of his position on same-sex marriage, and how his opposition was a matter of "intuition" rather than reason:
The best reason to worry about a change in how the state defines marriage was the fear of unintended consequences, of long-term ripple effects that could subtly but surely reshape society. But what might those consequences be? No one knows, or indeed if there will be any at all. Reduced to its essence, that fear is just another way to express one's gnawing anxiety at the prospect of social change. It is an intuition about what marriage should and shouldn't be, and I do not think that any intuition, no matter how strong or widespread, is enough to deny either a special classification or a set of state-defined benefits to a particular class of people.
Right. That's exactly why the case against same-sex marriage founders in court even as it proves popular electorally. In court, proponents of the ban had to explain exactly how heterosexual couples would be harmed by legalizing same-sex marriage, and they couldn't do it. In an election, appealing to people's fears and anxieties is enough.
