After Macbeth had killed King Duncan, he later regrets his wrong doing.
Lady Macbeth comes to the conclusion that to become king Macbeth must kill Duncan But neither in the successive murders of King Duncan, his two servants, Banquo, Lady Macduff and her children, is the least sign of courage shown by either Macbeth or his wife.
The influence of Macbeth's wife, Lady Macbeth, also contributed to his degeneration in character.
Lady Macbeth appears to become the catalyst for the predictions of the witches. When the witches told Banquo his future about a long line of kings to come, Macbeth thought it meant he would have a long line of kings in Scotland. Macbeth receives two new titles throughout the play; one is earned and the other stolen.
Lady Macbeth realises that the last thing Macbeth wants is to have his manhood questioned or being called a coward, as he thinks of himself as being a brave man, this makes him feel very reprehensible.