Marriage wasn't created "in tradition and the law." It was created by God, at the very beginning. In just the same way "up" and "down" were created by God. It is what it is. Tradition and law are forced to deal with these realities, and to be just and non-destructive they have to conform to them, but they didn't create them.
This is not a nitpick. It's very important. The camel's nose in the tent is the idea that men, or governments, have any kind of legitimate choice in matters of natural law.
The camel’s nose in the tent is the idea that men, or governments, have any kind of legitimate choice in matters of natural law.
...man has no legitimate choice in matters of marriage...?