Polygamy, cloning, fur, cheating and the death penalty are unacceptable. Abstained on gambling, but if I had to choose I'd say unacceptable as well. Everything else is acceptable.
Sobering numbers on out-of-wedlock births. I
Also, is it just me, or is there something a bit laughable about the fact that a majority of Americans say that it's OK to have children out of wedlock, yet very few who will claim that having an affair is acceptable? I'm not saying that it's incoherent, I just think that it's telling that more of us are bothered by a betrayal of our romantic ideals about marriage than we are about the failure of marriage as a structure for sustaining stable families.
A stable, committed relationship doesn't require marriage. Indeed, the former without the latter is increasingly common. While this trend might be unfortunate in some respect, calling it "morally unacceptable" strikes me as a bit of a stretch.