Discuss the importance of Macbeth's relationship with his wife especially with respect to his final suffering and tragedy in Macbeth?

By the end of Macbeth, the
relationship between Macbeth and Lady Macbeth has died, seemingly overtaken by Macbeth's
obsession for power and security.  In the beginning, Macbeth is persuaded by Lady
Macbeth to murder Duncan; Lady Macbeth chides Macbeth's manhood thus pushing him into
action.  However, once Macbeth has blood on his hands, he then is driven by his own
thirst for power and security and acts without her counsel or knowledge--she has no idea
that he plans to murder Banquo and Fleance, and she only realizes that Macbeth is
responsible for Banquo's disappearance and death when he sees the ghost at the banquet. 
Once Macbeth orders the murder of Macduff's family, Lady Macbeth then feels guilty
because she knows that Lady Macduff was simply an innocent party to all the turmoil. 
She feels guilty about her role in persuading Macbeth's actions and she thinks to
herself that no one knew how much rage Macbeth had pent up inside him.  After hearing
that Lady Macbeth has jumped from the window, Macbeth says that there is no time to
grieve--he is more concerned with the advance of the English army.  He says that Lady
Macbeth had to die sometime, and then he rushes off to tend to other affairs.  Macbeth
has no more allies and now even his wife is gone, and this is Macbeth's greatest
suffering and tragedy--he has no one who loves him as did Duncan, and because of it,
Macbeth knows that he has failed.