What is Marriage?

From yesterday's oral arguments before the Supreme Court...

Solicitor General, Donald Verrilli, as amicus curiae, arguing that there is a Constitutional right to same-sex marriage in the 14th Amendment on behalf of the Obama administration:

JUSTICE ALITO:  What do you think ­­­­ are the essential elements of marriage as it exists today?   

GENERAL VERRILLI:  Well, I think the essential elements of marriage are the ones that are ­­that­­ the, the obligations of mutual support and responsibility and the benefits surrounding marriage that State law provides to ensure that there is an enduring bond, that enduring bond that continues over time and lasts, hopefully, till death do us part, through the end of life.  And that,­­ and with and­,­ and, certainly, childrearing is bound up in that.

It is really difficult to make sense of this definition among all the stuttering (and coughing which didn't make the transcript), but here is a go at it:

Marriage is an enduring bond that continues over time and lasts, hopefully, till death.  And childrearing is (somehow) bound up in that.

So on that definition, if my wife and my brothers' wives were (God-forbid) to die, and we brothers were to choose to rear our children together, and we do so until we die, we would be married.  After all, we have an enduring bond that lasts until death and child-rearing is certainly bound up in that.  Bonus: I don't even have to make a till-death-do-us-part promise of fidelity; but it would be nice (maybe) if the bond continued until death (or maybe not.)

Notice that there is no mention that the bond be between two people.  That's not odd, for why should marriage be between two people rather than three or four (especially if they are sterile and have no children)?  Why hate on polyandrous marriages?  But a little later he summarizes his view of marriage with the following, again in response to Justice Alito:

JUSTICE ALITO:  As far as the, ­ the benefits that Federal law confers on married people, such as in Windsor, the effect on estate taxes, what would be the reason for treating [unmarried siblings who have lived together for 25 years and a same-sex couple who has lived together for 25 years and then gets married due to a change in law] differently?

 GENERAL VERRILLI: Well, ­ I, ­­ I'm not  entirely sure there would be, but, of course, marriage  is something more fundamental than that.  It is an enduring bond between two people.

Ah.  So marriage is an enduring bond between two people.  That is why the unmarried siblings should be treated differently.  [?]
And so I couldn't be married to both of my brothers.  But why couldn't I be married to one of them?  In fact, if I do have an enduring bond then I am married to one of them, it would seem according to this definition--that is, according to Verrilli, the definition of marriage which the Constitution has always recognized implicitly entails that. (Which brother I wonder?) Don't you tell me, hater, that we don't have an enduring bond!

Cue Justice Kennedy's infamously enigmatic statement in Casey v. Planned Parenthood:

At the heart of liberty is to define one's own concept of existence, of meaning, of the universe, and of the mystery of human life.

There's a Constitutional right to everything imaginable if you just look hard enough.