The first major threat to their relationship is Macbeth’s change of mind about killing Duncan: “We will proceed no further in this business” in Act 1, scene 7. This challenges Lady Macbeth’s dominance in the partnership. Ironically, it is their shared love that she uses as a weapon to regain dominance: “From this time/Such I account thy love.” Her aggressive and determined nature (“then you were a man”; “Have pluck'd my nipple from his boneless gums,/And dash'd the brains out” referring to a sucking baby), together with her simplicity of plot (drug the king’s guards), also impresses Macbeth:
Bring forth men-children only;
For thy undaunted mettle should compose
Nothing but males.
The strain of supporting her husband and adopting the male persona of a murderer has taken its toll; Lady Macbeth needs drugs of her own to dull her conscience (“That which hath made them drunk hath made me bold”), and even alcohol cannot suppress her natural compassion when confronted with a sleeping King Duncan: “Had he not resembled/My father as he slept, I had done't.” However, Macbeth’s love and admiration for his wife is so strong, he carries out the murder of Duncan alone: “I have done the deed.” Their language reveals the intense emotion that lies underneath the surface of their courageous exteriors: she uses the excuse of a resemblance to her father and both use euphemisms such as ‘business’ and ‘deed’ to evade the brutal reality of murder. Macbeth soon reveals the burden of his heinous crime that troubles his conscience: “wherefore could not I pronounce 'Amen'?”
Throughout Act 2 and Act 3, Lady Macbeth appears the stronger of the two in coping with the king’s murder, and she uses her typical blend of insults, encouragement and practical advice to bolster her husband’s fragile state of mind:
You do unbend your noble strength, to think
So brainsickly of things. Go get some water,
And wash this filthy witness from your hand.
They perform their roles of Thane and Lady, husband and wife, host and hostess perfectly, maintaining the pretence of innocence: “Woe, alas!/What, in our house?” and “The expedition my violent love/Outrun the pauser, reason”. However, the murder of Duncan marks the point where their relationship undergoes a shift: she is not as ruthless as she suggests (she could not kill the king) and he is not “full o' the milk of human kindness” as she originally thought. She has unleashed the killer in him and as soon as Macbeth is crowned King, she no longer has power to control him; it is noticeable that she faints in Act 2, scene 3 the moment that her husband confesses to murdering the king’s guards – this was not part of Lady Macbeth’s plan.
Once he becomes king, Macbeth seizes the initiative and makes his own plots against his rivals, Banquo and Macduff, without involving Lady Macbeth: “Be innocent of the knowledge, dearest chuck,/Till thou applaud the deed.” However, his language and tone towards his wife appears affectionate and caring. His protectiveness reveals a strong commitment to their relationship. Their private thoughts also reveal their commitment to each other; they both focus on the need for security and stability: “Nought's had, all's spent,/Where our desire is got without content” (Lady Macbeth) and “We have scotch'd the snake, not kill'd it” (Macbeth).
Their relationship is still intact, but their roles have reversed and Shakespeare uses language to illustrate this change; in Act 1 Lady Macbeth used the image of the raven as a portent of Duncan’s death (“The raven himself is hoarse/That croaks the fatal entrance of Duncan/Under my battlements”), Macbeth in Act 3 echoes his wife’s imagery in planning Banquo’s murder:
Light thickens; and the crow
Makes wing to the rooky wood:
Good things of day begin to droop and drowse;
While night's black agents to their preys do rouse.
For a short time during the banquet scene with the appearance of Banquo’s ghost and Macbeth’s hysterical reaction to it, it seems that Lady Macbeth reasserts her authority in the relationship. She is acutely aware of the public setting of the banquet and is resourceful in making excuses for her husband’s deranged behaviour: “The fit is momentary”, but privately insults his sense of manhood again: “Are you a man?” It is very likely that Lady Macbeth privately admits defeat: she dismisses the Lords at the banquet, but without dismissing their suspicions about her husband’s state of mind and his evil actions (“What sights, my lord?”), and her insults to her husband no longer have any effect – he has other plans that do not involve her (i.e. to visit the Witches for another insight into his future). Shakespeare creates pathos for the couple here, and especially Lady Macbeth; this is the last time the audience see them together and Lady Macbeth’s dejection is obvious in that she has very little to say and shows concern only for her husband’s lack of sleep.
The next time that Shakespeare presents Lady Macbeth in Act 5, scene 1, she is a pathetic, broken woman, unable to control her actions and words when she sleepwalks. Restless guilt and no visible support from her husband have driven her into madness. The sight of Duncan’s blood in Act 2 torments her: “Yet who would have thought the old man to have had so much blood in him?” But even in these moments of despair many of her thoughts return to the safety of her husband, always addressing him affectionately as “my lord” and using the first person plural “we”: Fie, my lord, fie! a soldier, and afeard? What need we fear who knows it?”
It is likely that Macbeth was better equipped to deal with this type of neurosis because he was aware of the burden of guilt from the first, whereas Lady Macbeth casually dismissed it: “Whose horrid image doth unfix my hair/And make my seated heart knock at my ribs” and “These deeds must not be thought/After these ways; so, it will make us mad”. Unlike the ever defiant Macbeth, who has to be killed in combat by Macduff as part of his revenge for the murder of his wife and children, Lady Macbeth capitulates and takes her own life – they die alone and apart. Upon receiving the news of his wife’s death, Macbeth initially seems unaffected and matter of fact: “She should have died hereafter;/There would have been a time for such a word.” However, the dejected tone of the remainder of this speech would suggest that he is deeply affected, feeling lost and aimless:
To-morrow, and to-morrow, and to-morrow,
Creeps in this petty pace from day to day
To the last syllable of recorded time,
And all our yesterdays have lighted fools
The way to dusty death. Out, out, brief candle!
Life's but a walking shadow, a poor player
That struts and frets his hour upon the stage
And then is heard no more: it is a tale
Told by an idiot, full of sound and fury,
Signifying nothing.
The dreariness of the alliteration and repetition, the fragility of the candle imagery and the futility of the acting imagery all suggest that Macbeth’s psyche cannot cope without his wife and his queen. Life holds no future or purpose for him, now she is dead.
After their deaths, their relationship is portrayed by Malcolm as “this dead butcher and his fiend-like queen”, forever united in evil. He began as a noble captain and ended as a bloody tyrant; she began as a devoted (some might say doting) wife, but ended up a guilt-ridden suicide. Their love remained until the end and their relationship, although subject to change and separation, remained firm.