Its not compassionate to children to put adult needs and desires ahead of them. Marriage is ultimately about raising the next generation. That's always been the argument for traditional man-woman marriage in a nutshell. That's why the institution matters. Most people agree with this view but a tiny minority wants to rewrite the age-old understanding of marriage cause it makes them feel left out. Its not about making a few adults feel good; its about making our children grow up safe so they can become responsible and productive members of society. That's what's at stake in the marriage debate. Too bad the U.S Senate doesn't get it.
Here is how I would put it. Let me preface this by reaffirming my steadfast opposition to gay marriage. It is a very important issue for me.
I don't blame gay folks for wanting it. The prevalance of traditional marriage does naturally create a disparity in the level of dignity enjoyed by long-term gay couples. That is not really fair, but life is not fair. The attempt to fix this unfairness is an example of a harmful attempt by liberals, libertarians, and even some conservatives to administer cosmic justice.