In the beginning of the play, Lady Macbeth does not think that her husband is strong enough to pursue his desires. She thinks that he is "too full of the milk of human kindness" to do anything ill to further his position. She knows that he has much ambition, but that he will not go after his goals. This is why she persuades him to murder Duncan and participates in the plot. However, at the end of the play, Lady Macbeth is surprised that Macbeth has become so evil, and she is surprised that so many people in Scotland have died at Macbeth's hand. She says that she never knew Macbeth had this in his character.
In the early section of the play, Lady Macbeth demonstrates that she is very devoted to her husband and truly aims to support his ambitions when she reads the letter reporting on the witches' prophecy. She essentially vows to ensure that Macbeth will get what he has been promised by whatever means necessary and then calls on spirits to give her the strength and malice to pursue this goal. However, Lady Macbeth also knows the loyalty that Macbeth feels towards Duncan and feels as though his kindness will impede his willingness to act in order to gain his ambitious goals. This is demonstrated by Lady Macbeth's continuous questioning of Macbeth's manhood and implication that he is cowardly. Moreover, upon completing the murder it is evident that Lady Macbeth finds her husband to be weak and even incompetent when he returns with the bloody daggers. This assessment of Macbeth as weak quickly fades to fear when Macbeth murders the guards to cover up their crime. Moreover, as the play progresses it is clear that Lady Macbeth feels more and more remorse for their actions while Macbeth seems to become more and more immune to the bloodshed. By Act 3, Lady Macbeth feels incredible concern for Macbeth's mental state, even begging him to sleep so that he might regain his original sanity back. It is clear that in the final section of the play that although Lady Macbeth does love Macbeth her intense fear and displeasure about who he has become ultimately leads in part to her own terrible end.