My first question is whether I am indeed correct in my understanding that the practice of both taking mistresses/concubines by noblemen was both widespread and acceptable. By acceptable, I mean the sort of thing for which there was no, even theoretical, objections most people would raise (jealously from a man's wife being some else entirely), and for which the person engaging in it would feel no need to conceal it, or that the practice would cause any sense of scandal. By comparison, I know that, at the very least, it was not unheard for clergymen to have mistresses, but as far as I know, catholic doctrine is rather clear on requiring the ordained to be celibate, and of course monks and nuns took vows of celibacy. Even if there were instances of clergy engaging in this practice as a sort of open secret, it was still objectively a violation of the "rules," as it were (at least after whenever it was that the church began to require priests to be celibate). If I am incorrect here, please correct me.

In any case, clearly the social mores have changed. If, for example, Prince William were found to have a mistress, this would be a huge scandal. I guess my question is what caused this shift in our understanding, in the west, of what marriage entails, in terms of what it means to commit adultery or to be unfaithful? Was this practice of sanctioned extramarital affairs something which included all men? Was it merely the noble? The rich? Was there a continuum? If I were, for example, to go back in time and accuse some monarch of committing adultery for having a mistress, how would he respond (besides, you know, executing me)? Would this claim even make sense to him? Now obviously, just because someone is Christian does not mean he or she is going to perfectly adhere to all the precepts of their faith. Obviously, there are many instances of noblemen engaging in unchristian activities. However, what has always confused me about the practice of them having concubines is that contemporary writers do not seem to decry it as sinful as they might for other activities. What I mean is that it does not seem to have been (generally speaking) something which was viewed as a moral failing, or something which was notable or unusual enough to make any more than passing reference to. In the same way, if I were to write some polemic about someone today, it would never occur to me to list his being married as immoral, perhaps he is abusive towards his wife, or the circumstances under which he married her were wrong, but the attribute of merely being married is not something either surprising or unusual enough to make specific mention of, or a negative attribute. That being said, obviously people's views are not homogeneous, so I would love to see counterexamples to my impression of the general views of the times.