What?
That's the worst argument ever. I could say "well heterosexuals dont have the right to join gay alliances or go to gay bars!", but that would be a retarded and pointless arguement.
We're asking for someone to be able to marry someone they LOVE. So not only gays, but transsexuals should be able to marry as well, if its love they're confessing.
Once again, that was a stupid arguement