Marriage is not an "inalienable right" ...if it were, brothers could marry sisters. We have all kinds of restrictions on who can get married. You can't get married if you are already married, you can't marry a person who has deceased, can't marry someone who doesn't want to marry you back, can't marry under a certain age, you can't marry immediate family members... you can't marry non-humans. If marriage were an inalienable right, this would not be the case, you could marry anyone at any time under any condition. So this is the first point of order we must comprehend before we go any further in this debate, marriage is NOT an inalienable RIGHT!
Then there is the matter of definition. Marriage is the specific union in matrimony, of one man and one woman. Anything else, is NOT traditional marriage, it is a perversion of marriage. You can't redefine what IS. It's like trying to claim the Moon and Sun are equivalent, on the basis that both are in the sky, appear to be the same relative size, and provide illumination.... they are still different, and the Moon can't be the Sun, ever. We can change the name of the Moon to the Sun, and it still doesn't make them equal, because they are what they are, regardless of what we call them. What you call "gay marriage" is simply "homosexual companionship" and nothing else. It can't be marriage, even if you want to call it that, because marriage has a specific criteria which homosexual unions can't meet.
No marriage license in the US requires you to affirm you aren't homosexual. That would have to be the case for gays to be denied the right to marry. As far as I know, gay people have the same opportunity to marry a person of the opposite sex, as everyone else. Although, there are still restrictions which apply, regardless of your sexuality. Inalienable rights can not be granted with restriction, they are inalienable. This reinforces the fact that marriage is not an inalienable right.