You have to remember that the first non-indigenous people in America were like Puritans and other religious zealots. It's really no wonder that it's permeated our whole culture.
And I live in Utah (which is only now starting to become less Mormon). When I was growing up as a non-Mormon it was probably 95% of my peers. So yeah, purity culture was definitely a thing. So many of my peers have terrible sex lives and marriages because of the emphasis religion plays.
I truly cannot imagine talking to a religious leader about my sex life. Honestly, gross.