@Christopher You make valid points, but I feel like your understanding is simply too extreme and unforgiving. Kaid only had so much power, both because he was only newly appointed as their ruler and because how young he was, and he may have had even less power as Helt. You say he could have done more, but what exactly could he have done? Should he have been so awesome that he should've been able to think of every possibility and be able to save her like it was a piece of cake? Or should he think like the 14-16 year old he was, in a situation that required him to hide his identity and dig up enough dirt to properly remove the nobles that were abusing their people? We don't know how much power he actually had, even up to her execution. Perhaps he couldn't have done anything even if he could think of a way to save her.
Honestly, the issue at hand seems to be that you and I simply have different values. You say condemn him, I say give him a chance. You say he's a "rapist," I say he's a victim of necessity. We both agree that what he did wasn't good, but I don't see him as an unredeemable villain nor do I think that it would be considered Stockholm Syndrome should she eventually learn to love him again. The love is gone, yes, but that doesn't mean new love can't be formed, whether it be from the ashes of the old love she once had for 16-year-old Helt or built completely anew after she gets to know this 30-year-old Kaid. He clearly means her no harm, and unless that changes if(more like when) he finds out that Shirley was the woman he executed then I don't think he should be considered a bad person. An imperfect person, yes, but not bad. With that said, this love ideally shouldn't happen till after she can overcome her depression and learns to love herself again, and most importantly she needs to understand that she isn't a bad person that deserves punishment.
My issue is that I simply wish you'd use a different analogy. What analogy? I don't know, but not rape. Kaid didn't kill her because he wanted to, nor does he wish to further inflict harm upon her, whether physical, mental, or emotional. A rapist, however, does it because they want to and take joy in what they do, and they will often wish to continue tormenting their victims. Could Kaid have done more? Sure, maybe. But at the time he didn't know what else to do. Maybe he was eventually able to figure out what he could have done differently after the fact, but that clearly would have been too late.
Despite everything I've said, it ultimately depends on how well executed this story is. Given the nature of her reincarnation and what she went through, how well the characters themselves are portrayed and how their love develops over the course of the series could make or break it. There are steps that need to be taken for both of them, and if the author rushes those steps or forgets them completely it could potentially kill any redeemable qualities Kaid has and the quality of the story as a whole.