I also agree that rape is morally wrong, but one can look around the world today and see that it is 'morally acceptable' in some countries around the world. While it is quite possible that a silent majority does not approve of such actions, it has been institutionalised in the legal and political systems of some governments. If the woman who is the victim, rightly tries to bring justice upon the perpetrator, she is the one legally found to be responsible. Then because of such 'daring do' to even suggest a man could do wrong, she's punished for adultery and then stoned to death or suffers the lash. Hardly fair, or even rational, but there is a modern day example of how something we find morally reprehensible, can be institutionalised and rationalised in some cultural groups.
Regarding rape, most societies do seem to consider it wrong, at least outside the context of war. The main problem is how you 'prove' it was a rape, meaning unwanted sexual violation. That did put a lot of pressure on the woman, of course.
From the laws of the Hittites ('the Code of the Nesilim'):
'If a man rape a woman in the mountain, it is the man's wrong, he shall die. But if he rape her in the house, it is the woman's fault, the woman shall die. If the husband find them and then kill them, there is no punishing the husband.'
The other laws seem to indicate that the Hittites were pretty liberal regarding sex, with the exception of incest, sex with animals (horses and mules excepted...) and married women. The law above has been the subject of some debate, but most probably it means that if a woman is 'raped' in her own house but didn't clearly make a lot of noise and kick up a fuss, she was assumed to have been willingly adulterous.
Sometimes 'kicking up a fuss' had to be quite demonstrative (as an example from a related society, see the case of the rape and suicide of Lucretia in pre-Republic Rome)
Things change again in 'traditional' societies when families are involved; if the rapist is a relative, or the member of a more powerful family, other social mores and considerations come into play. There are old Dutch songs where a girl is violated, and can't do anything about it due to her relatively lowly station, but there also others where her family pursues the rapist and 'Men deed den Ruyter knielen, al voor dat blanke zweert' ('they forced the knight to kneel before the naked sword', i.e. his head gets chopped off).
In short: rape is usually considered wrong in many societies, but proving it and getting justice done is something else entirely. This also applies to many other crimes like murder / manslaughter, abuse of power etc.
Regarding Tevinter, I suppose a somewhat standard pseudo-Christian (Andrastian) meets modern western liberal morality can be assumed, but with some modifications, but one that the powers-that-be and many members of society do no abide by.
Not unlike many modern societies in that respect, but probably much, much more exaggerated. Must keep 'em Tevinters in practice evil, of course.