Adultery

I found it ironic that the entire premise for Iago's deception is Desdemona's unfaithfulness, but in Act 4, Scene 3, she has a conversation where she admits to Emilia that not even for the whole world would she be unfaithful to Othello. She seems to truly believe in the sanctity of marriage, and she cannot see how anyone could be unfaithful to the love of their life. Iago, however, is doing his best to convince Othello that the very thing his wife despises is the act that proves she does not love him. His whole plans hinge on the assumption that Othello is gullible enough to believe his wife could do such a thing, and in reality, she claims not to be. She is perhaps the purest of them all, because she is the only one to refute the possibility of infidelity.