Virginity is painless

It’s easy for wild animals to choose the right time for their sexual initiation. For females it should happen whenever they are in season; for males it should happen whenever they get the chance. For you humans, of course, things are not so simple. In your world, the first sexual experience has a cultural significance unknown to wild animals. To be a human virgin is sometimes good and sometimes bad, but almost never a matter of no importance.
The human female does not normally mate as soon as she is in season. She is taught that her nubile body, with its unblemished treasure, is not be squandered on the first lecherous oaf who crosses her path. The logic behind this doctrine is sound. The young woman must seek impregnation by the best available male, and then rely upon his assets for the support of their offspring. To achieve this end, she must convince him that she is not the kind of sly wench who would bear the child of another man and pass it off as his own. The human male, for his part, will not commit his resources to any female unless he is confident that he will escape the fate of the cuckold. Thus, the unwed female has traditionally taken pains to preserve her chastity – or at least the appearance of it.