Eh... same-sex couples cannot file their Federal taxes jointly under any circumstances. See DOMA.
I know a couple of gay guys who would say “forget marriage, just let me sponsor my non-U.S. partner for permanent residency.” That’s a huge issue for people in my professional circle (law), which is pretty international. That issue also wins a lot of people over for favoring same-sex marriage, when they see their friends either staying separated or moving to Europe because of it.
They must be good friends. Your first page of posting history going back to May of last year is 95% on homosexuality-related topics. Are those the only topics you come here to follow?