I'm disappointed that you totally ignored my compelling counterargument to your claim that "Same-sex couples were never able to marry precisely because marriage was always understood to be--by definition--between a man and a woman." Compelling in the sense that I offered examples of SAME SEX COUPLES GETTING MARRIED. You say it's impossible, I'm saying I attended their weddings. One of us is very, very wrong.Oookay.
Now first, Rosenau seems to assume that if someone engages in the simple expedient of calling something marriage, it therefore is marriage. One more example of same-sex marriage opponents thinking that the normal rules don't apply to them.
Secondly, the advocates of same-sex marriage have denied that allowing same-sex marriage necessarily implies that other relationships could count as marriage--like polygamy, or humans "marrying" individuals of different species (notice how I crafted that sentence to avoid as much ickyness as possible). Given this, it is ironic that one of its advocates would make an argument that in fact, throws in the towel on that argument.
If Rosenau's logic is correct, then the fact that someone has attended a "wedding" between, say, a man and his dog, then that must have been included in the definition of marriage.
In other words, it's not that Rosenau didn't go to something, but that what he went to was not a marriage.