The goddess had never experienced the games of later generations; she would not know how frustrating and dissatisfied a person who was about to perfectly complete a level would feel in the face of a low-level mistake. She only knew how much energy she had invested before and how intense her desire for destruction was now.
"Sorry, Moira, I didn't know you were doing this for him—"
"Enough!"
In front of Demeter, Metanira still wanted to explain, but the goddess no longer wished to listen. The queen's voice only caused her annoyance, the more she cared for the child, the more it made the goddess realize that the other was a mother, whereas she was not.
So the game of pretense ended here... Since it was no longer perfect, it had no reason to exist.