To put things into “the” perspective…. the available evidence suggests that the genus Homo indulged/s in sexual activity more often for pure pleasure than conceiving an offspring.
The question then is, how did that come about? Again the evidence suggests sexual selection pressures.
Sexual selection pressure eventually results in sex- offered by a female- assuming a pivotal role in social interactions and becomes almost a commodity too.
While sexual selection is working behind the scenes, some individuals are born with mutations that make them sexually aggressive, hence these aggressive males pass on their genes easily through force (in an era when induced abortions were not possible simply due to lack of knowledge), the societies, as they are becoming larger and more oraganised, the sexually aggressive male behaviour becomes a crime and hence tries to impose an additive selection variable within sexual selection pressure.
Given this evolutionary history, sexual selection is the strongest selection pressure in humans today, eventually it will be superseded by technology, we will some day evolve out of this present predicament, which will take some thousands of years…
Until then, sex will be much abused by the society as a principal tool to control the masses because it has been and is the most powerful force which will determine the survival or wiping out of a society.