The species Homo Sapiens, as a primate species, shares rather universal social traits as its pimate cousins, the chimpanzees and the gorillas as well as the lower echelon of primates, the monkeys. Homo Sapiens, are considered apex predators and within the upper echelon of the primate species, and are naturally selective in partners, as other upper primate species such as the chimpanzees. Indicative of this is that chimpanzees choose a life long partner, and change only if the male decides to find another mate, or if one of the partners dies. The key for this is reproductive success, a law in the theory of natural selection and genetic variability. What is meant by this is that if a pair of chimpanzees mate and are capable of producing an offspring every spring, then there is a likely chance that that same pair will stick together to care for their offspring and repeat the same process due to the stability and factor of reproductive success. This is an innate plebiscite within all higher mammalian lifeforms, which is programmed in the hypothalamus and the basal ganglia, which is the innate urge to 'reproduce/procreate' and 'survive'. It is biologically logical for a successful mating pair to stick with other in times of environmental stress as a source of support, as well as this social structure will be strengthened with the changes of offpsring. However, if a mating pair is ineffective of producing an offspring, then most likely the male will find another mate in order to produce an offpsring, or rather, in some matriarchal-based social structures of some primate species such as the central african chimpanzee and the orangutan, the females will leave its male mate if that certain male mate is impotent and or unable to provide enough sustenance for the female and her offspring.
The homo-sapien, being the higher echelon of the primate species, has not only developed social etiquette as well as customs, provided via the larger cerebral cortex of our species as compared to our inferior primate cousins. However if you actually analyze the social customs of humans, in a behavioral sociological point of view, you will realize that there is a reason why there are 'courtships' and or 'dances', 'dates'. It is a form of male-showcasing, so to say, a way for the patriarchal figure to indicate that he is able to provide and protect the female, who is afterall the carrier of his future offspring. If the male fails in successfully wooning and courting the female, the female will find a 'better' male either one who is physically attractive (which is good for genetics, as a healthy mate will provide healthy genes for the offspring), or if the mate is capable of providing more sustenance and living conditions (doctor husband over the poorer blue collar husband; lawyer husband over the cashier husband, as an example). Its all about reproductive success, that is already pre-programmed in our central nervous system, and manifests the genuine complex nature of the human species as well as links us to our natural cousins, the monkeys, who also have this pre-programming.
Hope that helps
