marriage in the United States shall consist ONLY of the union of a man and a woman;..."(emphasis mine)...at least that's how I'd explain it.
Don't lose sight of the fact that over 70% of Americans are just fine with same sex marriages...I know it's tough being in such a small insensitive minority...but you don't have to stay there...read more about Senator Rob Portman's "coming out" in favor of such unions.