If the Constitution grants some broad, overarching, powerful “you can marry who you please” right, then it does so across the board. Polygamists, people who want to marry their siblings, all the rest of it. You can maybe carve out an exception for categorization based on age - but there is no way to have a broad right that doesn’t encompass pretty much all the grownups - whether or not that makes life difficult for legislatures and tax professionals, whether or not the relationship being solemnified offends the moral principles of the community.

If, on the other hand, the Constitution only provides a narrow right - “the following specific categories of people can marry, and nobody else” - then it’s perfectly legitimate to pick and choose which categories of people have the right. White people can marry, but not interracial couples. No gays allowed. Christian virgins between the ages of 18 and 34 - whatever the Constitution specifies. And if the courts find that the Constitution actually includes some new narrow group (gay couples, for example), then fine, they’re on the list.

Here’s the problem. The Constitution doesn’t do EITHER of those things. It doesn’t create a broad right for everyone to marry who they want, and it doesn’t create a narrow right for only certain privileged groups. It’s silent on the question - it’s left to the legislature.

That’s the problem I have when folks like DBB say “ooh, yay, the Constitution says there’s a right to marry!” The Constitution says no such thing, and when you ask where it says that, there’s no answer. It’s simply a court privileging its own narrow, provincial view over the narrow, provincial view of the legislature.

If there is a RIGHT to gay marriage (somehow, magically, implicitly in the text), then there is equally a right to polygamous marriage, equally a right to (consensually) incestuous marriage, and so forth. If there is a RIGHT to marriage in there, somewhere, then it applies to everyone - Mike and Mark, Jim and Jane and Jerry and Jen, EVERYONE.

You can construe, with enough intellectual lubricant, a universalist right to marriage, which of course includes gay people. What you can’t have is a universalist right to marriage which includes gay people but somehow conveniently excludes all the other categories of people who would also like state solemnification of their unions.