Macbeth is notorious for its inversion of traditional gender roles – Lady Macbeth is the dominant partner (at the play's beginning) in her marriage and she frequently browbeats her husband for failing to act like a "man" when he waffles about killing the king. Lady Macbeth isn't the only emasculating figure in this play – the weird sisters cast a spell to literally "drain" a man as "dry as hay" and set out to ruin Macbeth. It's important to note that traditional gender roles are ultimately reestablished by the end of the play when Lady Macbeth is excluded from all decision making and goes mad before she finally commits suicide. The play is also notable for the way it portrays femininity as being synonymous with "kindness" and compassion while it associates masculinity with cruelty and violence. (A seeming paradox given that Lady Macbeth and the witches are quite cruel. The point seems to be, however, that these women are "unnaturally" masculine.) Macduff appears to be a lone voice in the play when he argues that the capacity to "feel" human emotion (love, loss, grief, etc.) is in fact what makes one a "man."
For Lady Macbeth and her husband, masculinity is synonymous with cruelty and the willingness to murder.
In the play, women are portrayed as dangerous forces that can emasculate and ruin men.