I feel like that's a simplistic view
I would assume a majority of Americans either support gay marriage or are passive on the issue (meaning they don't really have an opinion either way and are not against it). However, you have to look at the people in power. You've got one of the two major political parties (The Republicans) vehemently opposing it and they hold so much power to veto the decision to allow gay marriage, regardless of what the average American thinks. The Christian right-wing holds a disproportionate amount of power in America, so even if they're a minority they hold a lot of political clout to have the greater say in matters. It's not so much about majority support, it's about who holds the power.
I would assume a majority of Americans either support gay marriage or are passive on the issue (meaning they don't really have an opinion either way and are not against it). However, you have to look at the people in power. You've got one of the two major political parties (The Republicans) vehemently opposing it and they hold so much power to veto the decision to allow gay marriage, regardless of what the average American thinks. The Christian right-wing holds a disproportionate amount of power in America, so even if they're a minority they hold a lot of political clout to have the greater say in matters. It's not so much about majority support, it's about who holds the power.
"Adulthood is like looking both ways before you cross the road, and then getting hit by an airplane" - sarcasm_only
"Ironically like the nativist far-Right, which despises multiculturalism, but benefits from its ideas of difference to scapegoat the other and to promote its own white identity politics; these postmodernists, leftists, feminists and liberals also use multiculturalism, to side with the oppressor, by demanding respect and tolerance for oppression characterised as 'difference', no matter how intolerable." - Maryam Namazie
"Ironically like the nativist far-Right, which despises multiculturalism, but benefits from its ideas of difference to scapegoat the other and to promote its own white identity politics; these postmodernists, leftists, feminists and liberals also use multiculturalism, to side with the oppressor, by demanding respect and tolerance for oppression characterised as 'difference', no matter how intolerable." - Maryam Namazie