Macbeth Question

[asheeline]

Why does Lady Macbeth doubt that Macbeth killed King Duncan?  What is it about Macbeth's character that makes her question her husband's willingness to go through with the murder?  

[asheeline]

From the start of the play Lady Macbeth has always doubted Macbeth's willingness to kill the king and when he says he does Lady Macbeth instantly doubts him. Lady Macbeth says, "Yet do I fear thy nature;/It is too full o' th' milk of human kindness." This is from act 1 scene 5, right after Lady Macbeth reads the letter; she thinks that Macbeth isn't man enough to do it.