After reading your post I agree, this is not soley and exclusively a L vs R issue. It is also a cultural issue. It is also an awareness issue. It is also an enlightenment issue. It is also an open-minded issue. It is a pro-family issue.
The frightened, the ignorant, the Xtian fundamentalist (but wait, I repeat myself....), the unenlightened, will, of course, fight giving basic marital rights to gays. Why? Because they are sore afraid. They are ignorant. They cannot see or view the world other than through the distortions of their religious prism.
I'm calling it as it is. As the genial 1960's anti-segregationist was a racist, so is today's anti-gay marriage voter a bigot. It may take a generation or two for this group of bigots to be flushed out of the mainstream body politic, after which they will no doubt congregate amongst themselves in secret, knowing that their backward views are anathema to right-thinking folk.
Gay marriage doesn't harm marriage.