Back when sex always entailed a chance of pregnancy, food was scarce, disease was a mystery, we lived in small tribes, etc. etc. many of these rules may well have made sense. Survival heuristics got encoded as religion, which was then horribly misinterpreted, and adhered to long past its point of utility. Now these rules aren't random, but they are pretty arbitrary.
Consider that our hangups about sex are tied to a sense of right and wrong that comes down to food scarcity (and other base needs, such as safety from predators) and reproductive rights. So we've got a bunch of people who treat sex as having moral significance owing to a survival/economic importance that no longer exists.
When sex first became disconnected from reproduction we had a "sexual revolution" where people tried to act as if the underlying rules and norms had changed overnight and there were horrible repercussions, but that's not because there's something intrinsically correct about our current (or recent past) sexual mores. Rape within marriage used to be just fine (indeed, it only became illegal throughout the US in 1993).
Consider that our hangups about sex are tied to a sense of right and wrong that comes down to food scarcity (and other base needs, such as safety from predators) and reproductive rights. So we've got a bunch of people who treat sex as having moral significance owing to a survival/economic importance that no longer exists.
When sex first became disconnected from reproduction we had a "sexual revolution" where people tried to act as if the underlying rules and norms had changed overnight and there were horrible repercussions, but that's not because there's something intrinsically correct about our current (or recent past) sexual mores. Rape within marriage used to be just fine (indeed, it only became illegal throughout the US in 1993).