I though that the ml's mother was dead?? How does he plan on getting a dead woman???
Sure! The young emperor was a lonely child due to his cruel treatment from royals and nobles. Grace was a caring mother to him when she visited the palace.
The young emperor used a ring that grants three wishes with horrible consequences. He used a wish to command Grace to be his mother and remain in the palace. She declined his wish which resulted in a consequence from the ring.
The consequence takes the life of the person that declines the command or wish. Grace declined his wish and died in front of him. He basically murdered her without knowing the consequences.
OMG I CAN'T STOP LAUGHING THEIR REACTIONS ARE SO FUNNY