Why are Americans so sexually frustrated and repressed?

I am from Europe and I've been living in US for a few years and the main thing that bothers me is that majority of women are sexually suppressed, and I don't see the logic in it, everyone is horny, why suppress it when you will be happier and more productive and healthier exploring your sexuality? is it because of religion? not only that but just an observation if you bring it up the subject is taboo, and when you date in US is like walking on eggshells not to offend these women....most of them consider the whole thing a guilty pleasure, and they go wild in vegas...witch it happens once a year if they are lucky...how did this population became like that? I find them to be very angry and judgmental (morality wise) towards the rest of the world...it's a very sad situation in US I don't think I would like to live here permanently. Luckily I am traveling to Brazil next but I am very curious why did this happens in US?