Which is why, of course, that marriage has existed and was defined as a union of a man and a woman since antiquity and long before there was any "official, enforced" definition. /sarcasm off
The only "official" definition of anything comes from our Creator, thinking that somehow you we need the government to define marriage in order for it to "exist" is a sad indication of how far people have been mislead to believe that the government is the granter of rights, or is necessary for ordinary life to proceed. Do you really think people would no longer fall in love and get married if they didn't have to go to the county clerk's office and fill out a form first?
Marriage has always been officially defined, when was it not. When was the time when Americans ever recognized marriage as anything other than what it is?
Remember when the Mormons tried your idea, and they had an army.