This falls out of the distribution of incomes even before any "preference". From a UK perspective, men outearn women on average, there are fewer female CEOs, m

This falls out of the distribution of incomes even before any "preference". From a UK perspective, men outearn women on average, there are fewer female CEOs, many well paying fields are 70% male, etc. If you pick a point on the income spectrum, there are more men in the country earning above that figure than women, and so unless you have incomplete pairing (same sex relationships likely don't change the ratios enough to matter) this is a trivial result.