beta
I have a theory that maybe Khalid might have been a spy for a while. It seems they grew up together on her past life so there's a chance that along one of their battles he got captured and that was the time he became a spy. My theory is that he might have killed her because he did not want her to suffer. There might be a chance that he knows they are on the loosing end (hinted during the time he presented her head to the king) and would most probably gonna be prisoners of war if that happens, Estelle being the commander will definitely gonna get the worst treatment, add to the fact that she was a woman, the treatment she would receive would probably even worst. Maybe... just maybe, in fear of an event of Estelle living while suffering he decided to just end her life and live as a dog of the kingdom he hates as atonement since death perhaps for him is just an escape for his sin of killing his comrade/or even possible love interest.
Or I dont know maybe he really is just a douchebag lol