My teacher once taught us that in the Middle Ages (maybe a little later but before the Reness.) there were an incredible number of criterias you had to meet. You could not have sex if the sun was up, not on Christian holidays (which there were a lot of), not on a Sunday and therefore not before or after a Sunday. The list went on and on.

At the end of it, there was ultimately very few days left in a year you could have sex on lol