Men are pigs

[LogGrad98]

IMO the short-term biological imperative is to spread our genetic material as far and wide as possible, as with all organisms that reproduce through sharing of genes (i.e. sexual reproduction). And most organisms have developed specific traits to attract another of the species with whom they can mate. Baboons have red asses, peacocks have big feathery asses, etc. So what are the physical traits that attract humans to each other? In all likelihood there is something there that attracts us to one another, on the basis of biology. It would be hard to explain why our general shapes (men with broader shoulders, generally larger overall, women with narrower waist, wider hips, generally smaller, etc.) have evolved the way they have if not for some form of selection based on biological attraction going on. To imply that what humans find attractive has nothing to do with biology and is driven entirely by our patriarchal society is short-sighted.

By the way, there is evidence of long-term pairing in hunter-gatherer societies, whether biological or not:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3083418/

Humans lived as hunter-gatherers for most of our species' history hence cultural variation amongst recent hunter-gatherers may be useful for reconstructing ancestral human social structure [8]–[10]. In a comparative study of 190 hunter-gatherer societies, Apostolou [11] showed that arrangement of marriage by parents or close kin is the primary mode of marriage in 85% of the sample; brideservice, brideprice, or some type of exchange between families is found in 80% of the sample; and less than 20% of men are married polygynously in 87% of the sample. The prevalence of marriage practices in hunter-gatherers suggests a deep history of regulated marriage. Brideservice and brideprice are often crucial economic components of regulated mate exchange, and low levels of polygyny indicate evenness of such exchanges. Here we further investigate marriage variation by adding time-depth via phylogenetic analyses in order to better formulate evolutionary sequences of derived human traits surrounding marriage (e.g., mate exchange, meta-group social structure, etc.).