Lady Macbeth's intent can also be interpreted as her belief that dwelling on the murder will weaken their resolve and disrupt their plans for seizing and maintaining power. By urging Macbeth to move on and not think deeply about their actions, she is trying to ensure that they do not become paralyzed by guilt or fear, which could jeopardize their ambitions. Therefore, the most fitting response is:
She believes that her husband’s weakness will harm his ability to rule.