There was a famous court case where the gay widow had no legal rights over their dying partners medical care, that is a pronounced human right that a heterosexual couple has over a gay couple that has been defined and why the opposition actually hurts people in ways many have not considered.

Remember that the compromise was "let gay people have those same rights, just don't call it marriage" and that was rejected. The opportunity to have that "pronounced human right" was always there but no, they wanted the culture war W of redefining marriage instead.