In act 1, scene 5, we see Lady Macbeth reading a letter from her husband in which he refers to her as his "dearest partner of greatness." Referring to one's wife as one's "partner" during the 11th century is pretty unusual; wives were usually subservient and were expected to be submissive to their husbands. It seems, then, that Macbeth loves and respects his wife. He even wants her not to "lose the dues of rejoicing" over his news by having to wait for him to come home to hear it. We see, also, that she feels she is more powerful than he and that she can manipulate him when she says, "Hie thee hither, / That I may pour my spirits in thine ear." She plans to tell him what needs to be done to make his fate come to fruition.
When Macbeth returns home, we see that he calls her his "dearest love" while she refers to him as "Great Glamis, worthy Cawdor"; his feelings for her are straightforward and clear, but her feelings for him more complex and bound up, perhaps, with his position. She does seem to love him, and she clearly knows him well, but she also asserts her power in the relationship. When he says that he'd like to speak further about their plans; she says to him, "Leave all the rest to me."
In act 1, scene 6, we see how easily Lady Macbeth "look[s] like the innocent flower," as she had discussed with her husband in the scene prior. She knows how to play her role, even though she was less confident about Macbeth's ability to play his. In act 1, scene 7, Macbeth says that he's changed his mind about murdering Duncan, declaring "We will proceed no further in this business." His wife berates and insults him, calling him a "coward" and suggesting that his love is worth as little as his promises. She says that, when he was willing to go after what he wanted he was a man; if he cannot bring himself to do this, then he is no man. She does manipulate and persuade him to go her way again, proving that she is—at least initially—the more powerful partner in this marriage.
In act 2, scene 2, Lady Macbeth tries to get Macbeth to move on after he kills Duncan. She fears, rightly, that dwelling on what they've done could "make [them] mad." When she sees that he's brought the murder weapons from the room, she is angered. She orders him back, and when he refuses, she says that he is "Infirm of purpose!" and is acting like a child. She implies that he is cowardly again when she refers to his "heart so white." She must remind him again of their plan.
In act 2, scene 3, Lady Macbeth slips up when she says, in response to the news that Duncan is dead, "What, in our house?" as though this were the important thing. Later, Macbeth goes off the plan again when he kills the guards his wife framed, and she must create a diversion—pretending to faint—to detract attention from it. We can see here that she is still more in control than Macbeth is but capable of making her own mistakes.
In act 3, scene 2, Lady Macbeth privately expresses her own anxieties, worries, and doubts that she does not share with her husband. He shares his anxieties with her, but he does not share his plan for Banquo—and this is the first time he has acted without his wife's prompting or input. We see the gulf between them beginning to open up as a result.
In act 3, scene 4, Macbeth's dinner party antics enrage and frighten his wife, who believes that he is hallucinating (as he hallucinated the dagger before killing Duncan). She asks him, "Are you a man?" implying that he is not. She tries to shame him before he reveals all their secrets with his raving. In the end, however, he says that they "are yet but young in deed," suggesting that they will have to spill a lot more blood to keep what they have; Lady Macbeth seems less sure. This is the last time we will see them on stage together, indicating how significantly their relationship has unraveled.
In act 5, scene 1, Lady Macbeth appears to relive, in part, the night Macbeth killed Duncan, but she also seems to reference her own guilt for everything Macbeth has done since then. She says, "The Thane of Fife had a wife. Where is she now?" She evidently knows that Macbeth has arranged the murder of Macduff's wife and children, and she says that "Hell is murky." This seems to indicate her own feelings of guilt—she believes she is in Hell. She helped to create a monster out of her husband, and now even she does not seem to feel close to him.
In act 5, scene 5, Macbeth has a pretty unemotional response to his wife's death. He simply laments how short and noisy life is and how it is ultimately meaningless, rather than expressing any kind of feelings or grief about her specifically. They have completely grown apart.