In the US we have a lot of places with abstinence only education, which I think would be fine if we also still had chaperones and courtship instead of dating.
But once you let boys and girls be alone together, you've basically given up on keeping them from going too far, so you need to teach them how to do it safely.
I feel like we would be just fine if we were serious about marrying as virgins, and we would be okay if we were serious about not worrying about it. (Not good, but okay. It would still be bad for the divorce rate.)
But instead we don't teach them OR supervise them, so we get all these diseases and pregnancies.