Marriage is a States Rights issue. Has nothing to do with the Federal Government. Dont understand why you need the State's permission to get married. It is mostly just to protect the people's right that get married. This is a racket created to earn lawyers money.
Again, marriage was originally invented for several reasons across many cultures. All the original reasons include legitimacy of heritage, ending of sexual rivalry, and transference of assets. Two of those have to do with government at the highest level. Otherwise you run into problems of one state not wanting to legitimize the legal status of a couples (regardless of the sexes of the couple).
Marriage is, and has been a tool of the government since time immemorial. It predates recorded human history. Saying that the government now no longer has a say in it is rather silly.