Midway through the play, specifically in Act Three, we find that Lady Macbeth is beginning to lose her power and strength while Macbeth, now the king, is at the same time finding his. For example you can tell Lady Macbeth is deteriorating when she states, "Naughts had, all's spent, where our desire is got without content: 'Tis safer to be that which we destroy than by destruction in doubtful joy. Enter Macbeth. How now my lord! Why do you keep alone, of sorriest fancies your companions making, using those thoughts which should indeed have died with them they think on? Things without all remedy should be without regard: what's done is done." As you can tell by that quote, Lady Macbeth is becoming quite uneasy and somewhat wishes she was the one being murdered instead of being the murderer. For Macbeth, he is becoming quite the daring fool. I say fool because he is exclaiming his hatred and urge to kill out loud. Like he says in this quote, "So is he mine, and in such bloody distance that every minute of his being thrusts against my near'st life. And though I could with barefaced power sweep him from my sight and bid my will avouch it, yet I must not, for certain friends that are both his and mine, whose loves I may not drop, but wail his fall who I myself struck down. And thence it is, that I to your assistance do make love, masking the business from the common eye for sundry weighty reasons." (Act III, Sc I) Basically Macbeth is convincing the murderers that Banquo is their enemy as much as he is to himself. Macbeth is also trying his hardest to cover up his dirty deed he committed to keep his clean status afloat. By the end of act three, Macbeth is showing his new strength and using it to his full advantage while Lady Macbeth is slowly starting to slip into her weak future self. .
By the end of the play, Shakespeare shows us a king who is using all of his power and strength to save his position, while showing how Lady Macbeth has lost all her strength and has slipped into an anxiety driven nervous wreck.
