Only 1 reason. Religion.
From the beginning religion held the female reproductive system as the entire worth of a female.
A few religions lifted the value of a woman because of the ability to create life.
Those religions are usual considered pagan.
Judeo-Christian and islam though took a different view. Since women were literally weak, and until now the World was RUN by Muscle, women were no more than property, and their value was in there vagina.
In all these cultures the transfer of wealth and power and a name from one generation to the next depended in Male children being born, and an CLEAR linage with it.
Because of the the Virginity of a female was ultra important.
Because of the - constant child birth was important.
Because of that, keeping your Possession (your woman) under thumb was needed.
Religion codified the suppression of woman and with this the suppression of Natural Sexuality.
Religion created a social structure where SEX was bad and only (semi)OK in marriage.
With that came the Dirt-if-ication of sex. Thats the only way to keep people in line with the way sex should be used.
Think of some of the words we use. Someone who has not had sex is - "pure" - or "innocent".
Think of the words we use for a woman how enjoys sex especially out of wedlock.
How many of those words are there compared to those for men who are sexual?
Religion took sex from being as normal and natural as eating - to being this EVIL Dirty thing that got you sent ot hell or had you stoned.
I could go on and on...