Could Lady Macbeth just be performed he duty as a wife? Perhaps she knows this is what Macbeth really wants, and so she must do all she can do to help him achieve that goal?

Macbeth's ambition is only eclipsed by that of his wife. She emasculates her husband in order to provoke him into doing things he just might not want to proceed with. Ambition and temptation both play a key factor in Macbeth and Lady Macbeth’s decision to kill Duncan. Macbeth possesses enough self-awareness to realize the dangers of overzealous ambition: “I have no spur / To prick the sides of my intent, but only / Vaulting ambition which o’erleaps itself / And falls on th’other” (25-28). And yet, the temptation to carry out the witches' prophecy is ultimately too strong for Macbeth to curb his ambition. In Lady Macbeth’s lexicon, incidentally, “hope” is also another word for “ambition” and perhaps “temptation.” As Macbeth expresses his doubts about killing Duncan, she demands: “Was the hope drunk / Wherein you dressed yourself” (35-36)? Ironically, Lady Macbeth must herself rely on intoxicants to “make [her] bold” before executing her ambitious and murderous plans (II ii 1). Once the intoxication wears off, Lady Macbeth finds that she is unable to cope with the consequences of her own "hope." Ultimately, ambition and temptation prove fatal for both the Macbeths.