In examination of the dynamic in the play Lady Macbeth is important for two primary reasons. The first is that she provides the extra degree to which Macbeth is able to undertake the morally bankrupt actions that come to define him. She does encourage him and ensure that he "close the deal." She provides the inspiration that the witches have already suggested, and what is already in his mind. Certainly, this is an essential part of her influence over him in the first part of the play. The second level of importance she occupies is to reflect how far off the path of happiness Macbeth is as he progresses through the moral bankruptcy of his actions. By the end of the play, we see both Macbeth and Lady Macbeth as a shell of the married couple they once were. As he has become more obsessed with protecting his ill- begotten gains, she comes across as being tormented with guilt and probably insane from it. When she speaks, we, as the reader, cannot feel a certain hollowness in recognizing that the weight of immorality has crushed the life and light out of this marriage. In this sense, she reminds us how bad things have devolved from whence they started.
In Shakespeare's Macbeth, Lady Macbeth's influence over Macbeth is vital. She is probably the primary influence that leads to Macbeth killing Duncan.
The witches heavily influence Macbeth, too, but they only predict to him that he will be king. Both he and Lady Macbeth turn that thought into a much more dangerous thought: you will be king, now, and you will get the throne by assassinating Duncan. Eerily, Macbeth and his wife take just a few seconds each to turn the thought of the prediction into the thought of assassination.
Macbeth falters, of course, and Lady Macbeth manipulates and ridicules him, questioning his manhood, and talks him into continuing. Her influence is vital and primary.
At the same time, though, though she is the primary influence over Macbeth, Macbeth is even more to blame. She is only an influence, he is the murderer. Niether the witches or Lady Macbeth actually do anything. Macbeth does. He is the killer. Lady Macbeth has an opportunity to actually kill Duncan herself, but she can't do it for sentimental reasons--the sleeping Duncan reminds her of her father. Macbeth can do it, and he does.
Thus, saying Lady Macbeth is the primary influence does not remove Macbeth's responsibility. His own ambition is central to his actions.
By the way, the play really doesn't show much of the relationship between the two Macbeths after Act 2.2. Macbeth shuts her out of the decision-making process and as far as the reader knows she has virtually no influence on him the rest of the play. She continues to berate him when he acts foolishly in public, but she plays no part in any of the murders except Duncan's.
In William Shakespeare's play "Mcbeth" the influence hat Lady Mcbeth has over her husband helps to set things in motion. When Lady Mcbeth hears from her husband about the prophesy that the witches have foretold she does not want him to wait to ascend the throne.
Lady Mcbeth convinces her husband that the throne has been stated it will be his so he should go ahead and kill the King rather than wait on something had to happen to him. She is ambitious and wants to be a queen.
Her influence over Macbeth sets off a chain reaction that will eventually lead to his death, her death, and the tragic events of the story.
Lady Mcbeth's influence is very important to the story line.