Judging by what we've seen in the previous chapters, she's killed a massive number of people in battle using superhuman abilities and her personality and morals have been affected by it.
I'm not really sure how I feel about the possible/future romance between the two. Its good that she's becoming a bit more human-like but I'm not sure how else this could end other than in tragedy. Its not that I want that to happen.
@Redwaterflowing same. Even if she becomes more human like, drama is bound to happen if she's the one who killed his parents. I hope when the drama comes, the author addresses it properly, I've seen way too many romances when the author don't address those things and give us a simple "I love her so I'll forgive her". The author will need to give her one hell of a backstory and a really solid character development if we want the love story to be credible. So far I really love the story, but I can't tell that I'm not anxious about how it's going to unfold.