How is Macbeth's suffering infinitely keener than Lady Macbeth's in Macbeth?
Macbeth suffers more than Lady Macbeth because he has to watch everything he gained crumble away.
Macbeth suffers because Lady Macbeth kills herself and ends her pain. She could no longer face what she had become, and neither could he. They responded different ways. She killed herself out of guilt, and he responded with denial.
Lady Macbeth was aware that she was complicit in guilt with Macbeth. She understand her role, and it was why she killed herself.
The Thane of Fife had a wife; where is she
now? What, will these hands ne'er be clean? No more o’
that, my lord, no more o’ that. You mar all with this(40)
starting. (Act 5, Scene 1)
Her comment about Macduff demonstrates that she felt responsible for what Macbeth turned into, not just the actions she forced on him. She convinced him to kill Duncan, but she also feels responsible for Macduff’s death.
Macduff suffers not just from his wife’s death, but from watching his kingdom crumble. He sees the wood come to the caste, and is assaulted by a man not born of woman. Macbeth thought he was safe, but he turned out to be vulnerable.