90% Women, due to low male births, males dominate society.

This world came to pass due to low quantities of sperm containing the Y chromosome.

However Males are the dominant gender in society they hold all the keys, wealth, power and each man takes up to 9 wives! To make sure no woman is lonely due to gender imbalance. It is automatically assumed all women are bi due to the gender imbalance in the society. And when a woman marries a man she also marries all his other wives. However a marriage without a man is not deemed legal, causing a black market in faux marriages to allow a man to gain power from marring into a powerful family.

It is expected a male would always take his first wife at 19, before leaving education, basically prom is a big joint marriage for the lucky few. Then men can marry up to 1 woman per year for rest of his life until he reaches his maximum of 9 wives

Sex can only accepted in society either in marriage or during courtship for marriage, no one night stands or wife swapping happens in the society.