I think there is political difficulty with the approach of pushing government sanctioned same sex marriage. Chipping away at government involvement in marriage takes the moral high ground and has prospect of enlisting the real majority: voters that are single. I think it would be tough to convince single folks to support and subsidize a program or law that gives benefits to single sex couples and not to single people. It is sort of like ML King saying we want civil rights for black folks, but not yellow folks. There are some weaknesses in the fairness and justice arguments.
