What makes Mary decide to cover up the murder in Lamb to the slaughter?

Answer 1

in lamb to the slaughter, it describes that her husband's head has meat pieces, and Mary was so urging for the investigators to eat her lamb.

Answer 2

Mary decides to cover up the murder in "Lamb to the Slaughter" because she realizes that her husband is planning to leave her, which would shatter her world. In a moment of shock and desperation, she uses the leg of lamb as a weapon and then fabricates a story to create an alibi for herself. She decides to cover up the murder to avoid the consequences of losing her husband and being judged by society.