Of course, while it fails democratically, it also triumphs legally. Being on the anti-democratic winning side helps make it the central issue of contemporary liberalism.
I stumbled upon this comment somewhere, but have lost track of who said it:
"To be against gay marriage, at least in the views of most liberals ..., is to disqualify oneself from society as a hateful bigot."
Gay marriage, for instance, is a trivial issue in real world terms, but it has become incredibly important to liberals precisely because it brands huge numbers of their fellow citizens as Dalits for them to hate and feel morally superior to.