I am not a lawyer either, but in my real life work had to do a lot of legal interpretation, so I think that I can pretend to answer like one in the absence of a real lawyer (one who I just pinged).
My guess would be that a real lawyer would say that any changes in future contracts (marriages) with new parties (men & women, men & men, women & women) does not change the terms of your legal contract (marriage). In other words, that you entered into a legal marriage when legal marriage required that only members of the opposite sex could marry, they would say that your marriage is legally unaffected by any future decisions the legislature might make re the rules for State sanctioned legal marriage.
Forgive me Kolokotronis, but that's what I meant about lawyers and politicians deciding what "a marriage is" -- it's like "casting peals before swine". The spiritual meaning of "marriage" is irrelevant in arguing law.
“The spiritual meaning of “marriage” is irrelevant in arguing law.”
Completely irrelevant and that is as it should be. As Orthodox Christians, we are not married because the state says we are, we are married because God’s Holy Orthodox Church through the Mysterium of Matrimony betrothed and crowned and joined us to each other according to God’s law. Marriage “contracts”, vaguely symbolized in the West by the exchange of vows, have nothing to do with us.
That the state says we are married in its eyes means we get certain benefits from the state and undertake certain state mandated obligations, some of which are co-extensive with what The Church teaches for marriage and some of which aren’t. “Gay marriage” is as much a creation of the state for purposes and reasons sufficient apparently for the state as male/female secular marriage is. It has nothing at all to do with us as Orthodox Christians.