Now Joseph Campbell doesn't understand history? No offense to your degree in Commerce, but I'll trust his lifetime of research and education over your convenient opinions.
I'm not too sure who is; ah, he had religious views on Jungian psychological archetypes (in addition to Commerce, I did a secondary degree on Social and Anthropological Psychology). While psychology is not my speciality, I did write a thesis on 'Religious Impacts on Human Sexual Behaviour', so I know a bit about all of this.
I'm not sure what Jungian archetypes have to do with middle class, working class and farm labourers marrying for love and not inheritance though. Actually, lower socio-economic groups didn't always marry, nor register childhood births (no birth certificates) until late in the 19th Century. They often used to live together, as we do now. The more you dig, the more confused it gets, no?
In which case, if it is not seen as causing emotional pain because it is a violation of the terms of the relationship, as it is popularly understood and discussed often in this very thread, this behavior would not be what is called "cheating," which is the topic of the discussion here.
You miss the point entirely. They had extra-relationship sex because that's what they wanted or, most likely, needed to do. In the African example I quoted, there was pain involved as the person who had the extra-marital sex had to be discreet, and conduct their affair in another village. In my Polynesian studies, there was reported emotional pain, particularly from men, but this didn't stop the practice.
Your repeated defense of "cheating," what is understood to be hurting one's own loved one for selfish desire, reeks of an intellectual defense for what you surely must strongly suspect is simply wrong.
There is no such thing as 'simply wrong'. If there was, all those hundreds of lectures and tutorials I attended were in vain. Instead of studying why we behave in certain ways, I could have had a Eureka moment and decided that certain behaviours are 'simply wrong'. And, therefore, the majority of human emotional conflict is solved!
The concept of faithfulness is driven by religious beliefs, which were driven by men's desire to control the parentage of their female partners offspring. If female sexual behaviours are controlled, then men have relevance in the line of inheritance. If female sexual behaviours aren't controlled, then male relevance is precisely zero. And that is the beginning, middle and end of why we insist on monogamy.
Judaism evolved by dumping Goddess worship (the whore of Babylon - look her up), and making the male father-figure the supreme spiritual deity, and making middle-aged men in charge of religion, and therefore in charge of society and therefore able to set the rules to the betterment of their gender. It really is that simple.
To understand where God comes from, think of the six universal spiritual deities. Peel them away, one by one, until you have one left. Indeed the deity of the fertile young man is represented, in Jewish/Christian terms, as the devil, so he arises from lust and desire. The whore of Babylon (Ishtar for the Babylonians, but also Innana, Isis etc) is the female counterpart of this deity.
Wow, your stats are off! And that's sidestepping the point entirely. If many people commit a wrong, it doesn't become right simply because so many people have done it.
Stats are correct, more or less, and I disagree that it's wrong, given that it seems to be a universal human condition.