I don't get it

I finally killed the princess for good and right before her death she told me that she always loved me. I find it rather confusing since we've been fighting for several endings, we've killed each other dozens of times. Not sure where this "love" narrative comes from. Was there something I missed? Also, sometimes the game won't allow me to slay her, and I'm forced to choose other options instead. I hope it will be patched.