I believe there is a misunderstanding we do not know yet, It is my speculation, but maybe he did not kill her, but he wanted to rescue her, but something went extremely wrong and her friend know the truth that he is not her friend murderer? I am sure author have a great explanatio for us later. We have even a clue when FL of this novel do not know what happend after death of Duke "she assume that this is the end of story"!!! But we are not sure
Makes sense. Tbh that's how it sounded like and I was sorta confused but yeah makes sense if we as readers don't know something yet.
Did I read it right? So in the past she was killed by the duke... then the duke and her friend fell in love and she knew who the real killer was so technically she loved her friends murderer?