Take a look at the United States Constitution, Article 4, Section 1:
"Full Faith and Credit shall be given in each State to the public Acts, Records, and judicial Proceedings of every other State. And the Congress may by general Laws prescribe the Manner in which such Acts, Records and Proceedings shall be proved, and the Effect thereof."
I don't want to get into a general exegesis of this article, but suffice it to say that this is the Constitutional backbone of the problem, and why a same-sex couple "married" in Massachussets may be able to force the governemtn of Arkansas to recognize the marraige. As written, Arkansas must give "Full faith and credit" to the public acts and records of the state of Massachussetts.
Now, the Congress has the right to legislate the "Manner in which such Acts, Records and Proceedings shall be proved, and the Effect thereof," but that does not extend to the substance of the issue, only the procedural issues of proof, i.e. does a marriage liscence need to be produced...
Now, if you are looking for explicit language dealing with recipricocity for marriages, you won't find it. The drafters were going for more general language when they put the Constitution together, but that doesn't mean that the clause as written doesn't cover marriage.
And are there any other instances of the Congress passing laws that say the courts do not have jurisdiction over a certain subject or topic?