I think that a case can be made to suggest that Lady Macbeth is responsible for Macbeth's death and he is responsible for hers. In this reciprocity, it becomes evident that malice and cruelty can be evident in both man and wife.
Lady Macbeth bears direct responsibility for the death of Macbeth's consciousness. There is much to indicate this in the First Act. Lady Macbeth's indication that Macbeth is not "man enough" to be able to forcefully seize the moment is reflected early on in the drama: "Yet do I fear thy nature; It is too full o' the milk of human kindness to catch the nearest way." Lady Macbeth uses shame and intimidation to remove Macbeth's sense of compassion and human dignity. The death of an almost child- like innocence is seen in the reference to "milk," reflective of youth and a sense of purity that she seeks to remove. She continues to berate him to a point where Macbeth feels devoid of any sense of redemption and spiritual righteousness:
What thou wouldst highly,
That wouldst thou holily; wouldst not play false,
And yet wouldst wrongly win. Thou'ldst have, great Glamis,
That which cries, 'Thus thou must do, if thou have it;(20)
And that which rather thou dost fear to do
Than wishest should be undone.”
Lady Macbeth is responsible for the death of Macbeth's sense of honor. Her word choice in how she speaks to him reflects an inversion. It is a mirroring of how "fair is foul" as that which is good has now become bad. As the drama progresses, the communication between Lady Macbeth and Macbeth reflects a discourse of death. When she speaks of the futility in seeking absolution or questioning motive of action with "Things without all remedy Should be without regard. What's done is done," he responds with how his mind is filled with "scorpions." In an instant, she recognizes that redemption is impossible, and the "milk of human kindness" as the human dignity within him is dead.
As Lady Macbeth recognizes the death of human compassion in Macbeth, he enhances this with his descent into a moral oblivion. Macbeth asserts to Lady Macbeth that "There's comfort yet; they are assailable.
Then be thou jocund" in recognizing how Banquo and Fleance need to be killed, continuing a cycle of violence that she started. While Macbeth's own moral degradation is evident, it is also clear that Macbeth is responsible for pushing away Lady Macbeth. His wife tells him that he "must leave this" and gain perspective through distance. Macbeth does not acknowledge this. In the process, he alienates her. As a result of such estrangement, Lady Macbeth becomes overcome with guilt and regret.
In Act V, it becomes evident that Lady Macbeth is overcome with guilt. No one understands this except Macbeth, yet he shows nothing in terms of compassion towards his wife. The doctor is honest enough to say that he cannot cure her as "the patient must minister to herself." Macbeth does not do anything help his wife. He is so far past the point of redemption that his wife becomes secondary. He tells the Doctor that he would praise him if he could save his wife. Yet, he himself shows nothing to help her. He becomes responsible for her death in his lack of action. In Act V, Macbeth becomes so driven by his own ambition that his wife becomes a casualty of a process that she started. It is in this where both bear responsibility for their emotional and physical deaths.
Macduff kills Macbeth, and Lady Macbeth kills herself. However, they are each responsible for their own deaths. While Lady Macbeth encourages Macbeth to remove all obstacles between him and the crown, we are all ultimately responsible for our own behavior. He provokes Macduff into killing him, believing in the witches' prophecy that "no man of woman born can harm Macbeth." Had he been more cautious, he would have considered the other possibilities, that Macduff was not technically "of woman born" but "untimely ripped" via Cesarian. No one made Lady Macbeth kill herself; she was driven mad by her own bloodlust.