What impact has the regicide had on his marriage?

Right after Macbeth is crowned, we see a huge change in the relationship between Macbeth and his wife. In Act I's initial scene, we see Macbeth making small talk with Banquo before meeting with murderers planning Banquo's murder. Lady MacBeth, who was originally the driving force behind Macbeth's murder of Duncan, is left out of any of Macbeth's plans from here on out. She says, "Naught's had, All's Spent, Where our desire is got without content." She is obviously not happy with their situation, and they essentially share little of their lives from this point in the play on.

Lady Macbeth gets what she asked for when she wants Macbeth to have the power he formerly was hesitant about getting. Once he gets that power, however, she seems to be a shadow of her former self, and no longer has any influence over him. He chooses the murderers to kill Banquo, puts spies in all of the nobles' houses, and plans the murder of Lady Macduff and her family. At no point, from the beginning of the third act on, does Macbeth feel any real need to share with his wife. Their constant purpose, maintained by the love they feel for one another, is no longer there. When she kills herself near the end of the story, we know that there is nothing left for her; soon there will be nothing left for him either.