No one is stopping gays from getting married. They can hold their ceremony, exchange their vows before their respective deities, live happy, fulfilling lives together and its all perfectly legal. None of this really has anything to do with the issue.
The issue here is who gets the legal goodies? A gay man and gay woman who want legal goodies, can get "married" according to the state and be entitled to legal goodies. They aren't being prevented from getting goodies on the grounds that they are both gay. The argument here is always that a gay man and a lesbian wouldn't want to marry each other because they aren't sexually attracted to each other.
So my question is why sex is a prerequisite to getting equal treatment under the law. How is my relationship with my best friend, or with my sister, or with my grandpa, or my business partner, or my flight instructor, or anyone else I have a relationship with less deserving of privilege simply because it is not a sexual relationship?
Things like power of attorney, and living wills, and inheritance rights, and everything else on the list of rights that gay marriage folk are fighting for should have nothing to do with sex at all. I should be able to get all those privileges with my brother if I so choose. They should have nothing to do with marriage at all.
Legalizing "gay marriage" won't get rid of oppression. It will just move gay married couples from the oppressed class to the oppressing class. That isn't progress of any kind.