I don't think Americans are yet ready for a first lady who's the president's husband.
I would have thought the same thing until they elected the current title holder. If a guy who pushed the birther thing for that long and can still hold the religious right's support after grabbing pussy can get elected, all bets are off, I'd say.
But on the more general theme, if liberty, freedom, privacy and the pursuit of happiness are so important to Americans, why would anyone think it's any of their business who others have sex with. It's a puzzling thing. It's possible that people don't truly understand what freedom means.