Yes, but we can't imagine such a scenario happening in reality. That's what gives you the illusion of some moral values (not even all) being something superhuman.
Excellent B-movie plot, but it won't happen in reality. And fully contrived to make non-believers look like immoral oppurtunists. Anyhow I'll play along and assume it could happen. Well, then that would be an immoral sadistic bastard of a king to start off with, right? How do we respond to immoral actions? Normally by trying to stop them. That's why we invented democracy in reality. So, also assuming that we can't undermine this king's power and we have to make a choice given the only 2 possible options, then yes, at some point the hardship the poor family has to endure will overcompensate the hardship caused to the woman by raping her. This example also nullifies one of the main purposes or morality, which is avoiding that individuals do something for personal gain (in reality the personal gain of rape is the derived pleasure) that will in the long run (usually if everybody did it) would significantly harm society and thus every individual too.
Now, why don't you stop giving Planet-of-the-Apes-esque examples and try to make a general statement. I gave you 3 solid reasons why it doesn't make sense to postulate absolute morality. You have ignored them and keep making up examples that don't lead to a general conclusion.
Very well.
I will give you many reasons why it does not make sense to postulate ethical relativism.
1)
While the moral practices of societies may differ, the fundamental moral principles underlying these practices do not. For example, in some societies, killing one's parents after they reached a certain age was common practice, stemming from the belief that people were better off in the afterlife if they entered it while still physically active and vigorous. While such a practice would be condemned in our society, we would agree with these societies on the underlying moral principle, the duty to care for parents. Societies, then, may differ in their application of fundamental moral principles but agree on the principles.
2)
It may be the case that some moral beliefs are culturally relative whereas others are not. Certain practices, such as customs regarding dress and decency, may depend on local custom whereas other practices, such as slavery, torture, or political repression, may be governed by universal moral standards and judged wrong despite the many other differences that exist among cultures. Simply because some practices are relative does not mean that all practices are relative.
3)
If the rightness or wrongness of an action depends on a society's norms, then it follows that one must obey the norms of one's society and to diverge from those norms is to act immorally. This means that if I am a member of a society that believes that racial or sexist practices are morally permissible, then I must accept those practices as morally right. But such a view promotes social conformity and leaves no room for moral reform or improvement in a society. Furthermore, members of the same society may hold different views on practices. In the United States, for example, a variety of moral opinions exists on matters ranging from animal experimentation to abortion. What constitutes right action when social consensus is lacking?
4)
Universal moral standards can exist even if some moral practices and beliefs vary among cultures. In other words, we can acknowledge cultural differences in moral practices and beliefs and still hold that some of these practices and beliefs are morally wrong. The practice of slavery in pre-Civil war U.S. society is wrong despite the beliefs of the society itself. The treatment of the Jews in Nazi society is morally reprehensible regardless of the moral beliefs of Nazi society.
Just because the Nazi's believed their actions were morally justified, that does not deem their actions moral.