When Victor Frankenstein decides to destroy the female creature he was creating, he does so out of fear and a sense of moral responsibility. After creating the Creature and witnessing the devastating consequences of his experiment, Victor is filled with remorse and guilt. The Creature demands that Victor create a female companion for it, promising that they will leave humanity and live in isolation.
Initially, Victor reluctantly agrees to create a female companion for the Creature, hoping that it will mitigate the Creature's destructive tendencies and provide it with companionship. However, as he progresses with the new creation, he begins to consider the potential dangers of having two powerful and unpredictable beings like the Creature in the world. He fears that the pair might procreate, leading to a race of monsters that could threaten humanity.
Fueled by these fears and moral dilemmas, Victor ultimately destroys the unfinished female creature. The Creature, witnessing this act, becomes enraged and threatens Victor, vowing to take revenge on his creator by causing suffering and misery.
The destruction of the female creature marks a critical turning point in the novel. Victor's decision sets off a chain of tragic events and confrontations between him and the Creature. The Creature proceeds to fulfill its promise of vengeance by causing harm to Victor's family and loved ones, leading to further devastation.
Victor's destruction of the female creature illustrates the moral complexities of his actions and the ethical implications of playing "God." It reflects the novel's exploration of the consequences of unchecked ambition and the responsibility of creators toward their creations. The act also deepens the rift between Victor and the Creature, culminating in a final confrontation that carries significant consequences for both characters.