Lady Macbeth shows internal conflict when she compares Duncan to her father and when she imagines blood on her hands. These techniques are foreshadowing and metaphor.
When Lady Macbeth finds out that her husband heard witches tell him that he was going to be king, she jumps on the opportunity. She does not feel that her husband has it in him, but she pushes him until he finally kills the king.
Lady Macbeth is the one who devises the plan and forces Macbeth to follow it, but she does not kill Duncan herself. In fact, she notes that he looked so peaceful that she was unable to kill him.
Alack, I am afraid they have awaked,
And 'tis not done. The attempt and not the deed
Confounds us. Hark! I laid their daggers ready;
He could not miss 'em. Had he not resembled
My father as he slept, I had done't. (Act 2, Scene 2)
The internal conflict here is that Lady Macbeth is beginning to doubt the plan to kill Duncan. This is also foreshadowing for her later mental breakdown. She saw Duncan, and he looked like her father, and something inside her began to unravel.
Macbeth is going downhill too. At a banquet, he thinks he sees the ghost of Banquo and freaks out. Lady Macbeth begins to doubt what they have done again. She makes excuses for Macbeth, saying nothing is wrong with him and he often gets such fits. In reality, things are falling apart for her.
Everything comes to a head when the battle is imminent. Lady Macbeth has to face what they have done, and something inside her finally snaps.
Out, damned spot! out, I say!--One: two: why,
then, 'tis time to do't.--Hell is murky!--Fie, my
lord, fie! a soldier, and afeard? What need we
fear who knows it, when none can call our power to
account?--Yet who would have thought the old man
to have had so much blood in him. (Act 5, Scene 1)
It is not long after this that Lady Macbeth kills herself. Here she imagines blood on her hands. It is too much for her. She feels like she is seeing King Duncan’s blood and can’t wash it off. The blood is a metaphor for her part in Duncan’s death.
Shakespeare uses these two techniques, foreshadowing and metaphor, related to Lady Macbeth’s internal conflict. Macbeth also suffers from what they have done, but his reaction is to continue killing to try to stay in power. Lady Macbeth kills herself from guilt.