Marriage is an abstraction invented by humans. This is why the details vary from culture to culture. Humans didn't invent gravity. This is why it is the same i

Marriage is an abstraction invented by humans. This is why the details vary from culture to culture. Humans didn't invent gravity. This is why it is the same in the US as it is in Asia, as well as everywhere else in the universe. Thus, gay marriage can easily exist. People simply have to believe that it is a useful abstraction.