Why did Frankenstein's monster kill elizabeth?

Frankenstein's monster killed Elizabeth as an act of revenge against Victor Frankenstein, her husband. The creature was deeply hurt and enraged by Victor's rejection and abandonment, feeling that he was denied companionship and love. By targeting Elizabeth, the monster sought to inflict the same pain on Victor that he himself experienced, ultimately highlighting the tragic consequences of Victor's refusal to take responsibility for his creation. This act underscores the themes of vengeance, isolation, and the destructive nature of unchecked ambition.