The National Organization for Marriage has been going around for a few years with their "gays are icky" opposition to marriage equality. But I don't think these people really understand marriage, which they are claiming to defend.
To me marriage allows two people to create a little world in which they can live, free, or at least freer, from the sort of intrusions and uncertainty that single life entails. I don't about you all, but for me, dating was not a good situation, and the sooner forgotten, the better. I think many people, if they were open about it, would be willing to state that their single days were not the glory times of swinging hedonism, but rather a time of emotional stress.
I understand that there once was a school of psychological thought that claimed that children were not affected in a permanent way by the divorce of their parents. I have some personal experience with that and I can tell you that whoever may came up with that theory never talked to me. I could have given them a new data set to work with.
Fortunately, most married people don't think about having affairs, and most people looking for an affair stay away from married people. If things were otherwise, we wouldn't pay attention to or talk about it when married people did have affairs.
I mentioned that marriage allows the creation of a private world. Legally this is certainly true. Somewhere I read that there are 1,000 legal advantages for people who are married over people that aren't. I don't know about that, but for sure, within broad limits, the government cannot tell anyone who to marry, and certainly the government is powerless to dissolve a lawfully contracted marriage. Marriage is the classic "small government" measure.
So, with all these advantages, why should I want to restrict them to cases where Jack marries Jill. If Jack wishes to marry Jack, or Jill wishes to marry Jill, what is it to me? If I really were a "small government" conservative, shouldn't I be welcoming the move of Jack and Jack, or of Jill and Jill, to construct a world in which the say of the government is sharply limited? Do I wish for the government to compel them to continue to endure, as many do, the emotional stress of single life?
Someone I suppose could say, and they have, that the marriage of Jack and Jack or Jill and Jill is an abomination in the eyes of God (as if she has nothing else to worry about.), and that only the marriage of Jack and Jill is approved by the Almighty.
If that is so, then let all the 1,000 legal advantages enjoyed by married persons be entirely rescinded. Then we'll see whom the Goddess may truly favor once the legal playing field has been leveled. But, since I don't see how this is politically likely, or even desirable, then the only fair thing to do is to extend them to Jack and Jack and Jill and Jill.
So, forget about liberalism. I don't think that opposition to marriage equality is even conservative.