@drag0nb0rn
Backstories are good reasons as to how readers can get more into particularly evil acts of revenge. Sure you could have the hero or anti-hero raping the princess in the first chapter, but you would still want to read why exactly, unless the earlier parts of the chapter shows that and rape comes towards the end.
I mean, if you compared someone hitting a woman in the first chapter in the introduction to the say situation in either the 2nd chapter or 2nd chance, playthrough whatever, and we know that woman has done terrible things to him and deserves way more punishment than that, people would go from 'Does she really deserve that?' to 'That's nowhere near as much as she deserves coming to her!'
That being said, there's certain varieties on how the events can play out, which are interesting to wait for. Princess is out for something bad yes, but will he deliver it on his own or add emotional / mental damage by having her people do it to her instead, promising life to the end that humiliate her the best? And he spared the female knight this chapter, so using her is a chance as well.