Shakespeare's Macbeth differs from other tragedies in that Macbeth's character so dominates the play that audiences are compelled to identify with him, terrifyingly, as a matter of fact, because with the early removal of Lady Macbeth from the drama, they perceive in his imagination that which is also frightening, thus lending what critic Harold Blooms terms "our terrified sympathy."
That Macbeth is profoundly dependent upon Lady Macbeth as mother/wife is clearly evinced in Shakespeare's play. When she "unsexes" herself to propel Macbeth along the path of ambition, she commits a fatal error. For, although she succeeds in stirring him to kill Duncan, having unsexed herself and challenged his manhood in Act I, referring to his battle exploits--"then you were a man"--and chiding him in Act III when he sees Banquo's ghost--"Are you a man?"--she unknowingly plans her own murder. For, once she no long demonstrates any femininity, Macbeth rejects her and, according to Bloom,
...murder increasingly becomes Macbeth's mode of sexual expression.
Thus, there is great poignancy to her cries of "To bed" in her madness because her husband has abandoned this conjugal bed. She also loses her role as mother to Macbeth;and, having born no children she has no hope of renewal of this motherhood. So, Lady Macbeth becomes guilt-ridden because of her earlier actions and, ironically, in order to re-humanize herself. With the valid emotion of guilt, she can, then, turn to domestic functions and her role in protecting her husband.
Wash your hands, put on your nightgown;
look not so pale. I tell you yet again, Banquo's buried; he
cannot come out on's grave. (5.1.56-58)
This re-humanizing of Lady Macbeth, however, is futile because she yet fails to regain Macbeth as her husband. It is only after her death that Macbeth mourns her in his soliloquy of regret.