How does love affect Lady Macbeth?

Unlike many marriages among the nobility, who often marry for money or political connections, it does seem as though there is real love between Macbeth and Lady Macbeth.  When he writes to her, he calls her "my dearest partner of greatness" and expresses his desire to acquaint her with what the Weird Sisters told him so that she "might'st not lose the dues of rejoicing by being ignorant of what greatness is promised [her]" (1.5.11, 1.5.12-13).  In calling her his "partner," Macbeth signals the equality in their relationship, and in expressing his wish that she feel all the joy of his news as soon as possible, he shows how much he truly does care for her feelings.

When he arrives at their home, he refers to her as "My dearest love," and they have a very familiar exchange (1.5.67).  It is clear that each knows what the other is thinking, and they do not even have to speak their intentions aloud in order to know that the other is on the same page.  When she asks when Duncan will leave their home, Macbeth says, "Tomorrow, as he purposes" (1.5.70).  In other words, Duncan will leave tomorrow -- or so he thinks.  Macbeth and Lady Macbeth are two peas in a ruthless pod.  She tells him, "Leave all the rest to me," assuring him that she will take care of the entire plan (1.5.86).

Their love seems to affect her insofar that it makes her want to take care of him.  She is concerned that he is too gentle and compassionate to find the quickest way to the throne, and so she nudges him to do whatever is necessary for their mutual success.  It is difficult to determine how much of this can be imputed to her desire for power or to her desire to see him in power.  In a twisted way, however, she wants power and she wants it with Macbeth, and it is only after he begins to make plans without her (such as arranging for the murders of Banquo and Fleance as well as the Macduff family) that she seems to give in to her guilt.  After the banquet scene, we no longer see this once-happy couple together; we only find out her response to the murders of the Macduff family when she sleepwalks.  Her love for Macbeth essentially leads her to create a monster she can no longer control, and she ends up killing herself as a result of it.