Thoughts on Marriage

I'm seeing posts about marriage... in general and regarding same-sex marriages. For the most part they seem to me to defy logic.
If marriage is a civil state prescribed by law then how is discriminating against same-sex marriages not a violation of those folks' civil rights?
If reproductive capacity is an issue then I have another problem... I'm 57 and my wife is 52. Still Franklin County, Florida gave us their blessing.
I hear about the "sanctity of marriage"... I'm not sure exactly what people mean by that... adultery doesn't seem to be much of an issue... divorce doesn't seem to be a show-stopper.
Honestly, it seems to me that... as much as anything... the anti-gay folks just don't want to see homosexuals leading happy, (otherwise) normal lives. That's what I make of it... pure meanness... and that's sad. Where does that kind of unhappiness come from that one would begrudge the happiness of others?
I've been married four times. I've been wrong before. I mean to do everything in my power to stay by this good woman's side so long as I live... and I sincerely hope that every man and woman on the face of this earth finds, recognizes, and enjoys this kind of happiness.