See post 43, the “states” argument is an argument for gay marriage.
As I mentioned elsewhere, state power to regulate marriage is not a matter of opinion. State power to regulate marriage is protected by the 10th Amendment, plain and simple.
Regarding the Full Faith and Credit Clause, the Constitution's Section 1 of Article IV which I think you are basing your opinion on, please note the following. Before Congress established the constitutionally indefensible federal drinking age law for example, a 19-year old living in a state where drinking age was 19 couldn't go to a state where drinking age was 21 and buy booze on the basis of the Full Faith and Credit Clause.
What's going on is that pro-gay supporters, which maybe includes you but certainly activist justices, are pushing the gay agenda on PC interpretations of both the Equal Protections Clause of Section 1 of 14A and the Full Faith and Credit Clause.
Whatever ever 'gay couplings are' they are NOT marriage. That is self evident.