Hypothetical on gay marriage

So lets say you have a married couple, standard man-woman thing. One of the couple decides to get a sex-change operation, and afterwards the couple is now man-man or woman-woman. Would they still be considered married in a state where gay marriage is prohibited? Would it matter whether the change was done with or without the consent of the other spouse?

Gideon muses on the permutations of gay marriage, without finding an optimal solution.