It's honestly this easy;
*States just need to create a new type of license with additional benefits which is only available to opposite-sex couples. (The end result is that what's considered "marriage" now becomes the new "civil union", and the new license in question becomes the new "marriage"; available only to couples of the opposite sex).
*The Supreme Court just needs to rule it Constitutional (and with a court stacked with 6 conservative judges to just 3 liberal ones, this could easily happen)
And voila! Same-sex "marriage" is now gone like it never existed.
*States just need to create a new type of license with additional benefits which is only available to opposite-sex couples. (The end result is that what's considered "marriage" now becomes the new "civil union", and the new license in question becomes the new "marriage"; available only to couples of the opposite sex).
*The Supreme Court just needs to rule it Constitutional (and with a court stacked with 6 conservative judges to just 3 liberal ones, this could easily happen)
And voila! Same-sex "marriage" is now gone like it never existed.