How has Desdemona and Othello's relationship changed since the beginning of the play?

"O, the world hath not a sweeter creature," Othello declares of Desdemona; yet, against his reason and better nature, he decides that she shall not live for what she has supposedly done. There is great irony in this scene, as Othello declares that Desdemona is of a soft and kind nature, yet condemns her for being lustful and immoral. Note Othello's reticent tone, even when he is condemning Desdemona to death; although chaos and jealousy have triumphed over reason, still there is a part of him that knows Desdemona is good, and does not want to condemn her.

When Othello strikes Desdemona, he shows the severity of his change. Just her mention of Cassio sends him into an unreasonable rage; every little thing he regards with suspicion, even if he has no cause. Although one of his greatest fears regarding Desdemona's alleged infidelity was that it would blacken his name and reputation, the irony is that Othello is doing that himself; in striking Othello and being unreasonably cruel, he besmirches his own good name. Savagery is taking over his civility, as he continues to become the cruel, jealous, passion-spurred "savage" that Brabantio accused him of being. He is beginning to become a stereotype by his own doing, as he falls farther and farther from himself.