It's often said that women trade sexual access for provisioning and protection. I think there is obvious truth to this, but the evenness and/or fairness of this 'bargain' depends on the context. Let's examine this bargain on a macro level during the modern context.

1.) Male labor ≈ female labor + pregnancy and child rearing

In a modern context, we assume that the typical man and woman put in equal overall effort; and they are roughly of equal capability. By and large, any extra productivity and/or time put into work by men is a result of the demands of pregnancy and child care, which benefit both genders equally. Furthermore, child rearing is increasingly split between both genders, and/or partially outsourced and paid for by the labor of both genders.

Because of superior male physical attributes, there is still an overall male superiority in terms of labor productivity net of pregnancy costs. But the source of this advantage is diminishing rapidly in the modern world. Furthermore, we are seeing evidence that women are naturally more adapted to many modern workplaces (better at sitting still, dealing with monotony, etc.) So if there is still an overall surplus on the male side of the labor ledger to trade for sexual access, it is small and declining. It is also possible the surplus could shift to women over time, as labor conditions continue to shift from tasks that reward male characteristics to those that favor female.

2.) Male Protection Providing (greatly diminished on a per capita basis) + Doing More Dangerous Jobs ≈ Female Protection Providing (still much lower than male) + Dangers / Physical Costs of Childbirth (also far lower than they were historically)

In advanced industrial democracies, it's hard to see that much of a male surplus on the 'danger' side of things when we get to a per capita basis. And as with labor, the trend is for whatever surplus is still on the male side of the ledger to increasingly diminish as technology advances.

If we look back at history, it seems clear that as we have advanced, the aggregate value of the male surplus on the provisioning and protecting side has been in steady decline. Given how much many women inherently dislike providing sexual access to men they do not inherently desire, it seems to me that for a while now widespread monogamy has been facilitated by artificial means.

By rewarding male labor with a disproportionate amount of resources compared to the effort, society made it possible for men to provide the amount of resources needed to entice women to trade sexual access for said resources. Gendered division of labor probably made sense in terms of efficiency for much of history; however, by essentially paying women nothing for their work, it put them in an artificial position of economic dependence and scarcity so that men were in a position to make the classic resources for sexual access trade. The obvious goal of this was to override the innate sexual selectivity of female choice without having to physically coerce every woman, which is far less efficient. This overriding of female sexual selectivity was the only way to make widespread, enforced monogamy work.