How has the relationship between Macbeth and his wife changed since the death of Duncan? Think about Macbeth's view of Duncan's murder, Lady Macbeth's view of Duncan's murder, Macbeth's refusal to tell his wife about his plan to murder Banquo, Macbeth's "fit' at the banquet and his wife's reaction to it.
They have grown closer to one another out of necessity. They are unified in their shared disgrace and their mutual interests. Furthermore, their roles have inverted since earlier in the play. Whereas before Lady Macbeth was the ringleader, now Macbeth has taken charge of planning and executing the malicious activity necessary for their goals to be realized. He preserves Lady Macbeth's innocence with regards to Banquo's murder and handles it himself.