Othellos tragic flaw is his jealousy. His feelings of inadequacy are felt sharply though his colour and the fact that he does not actually belong in Venice.

He clearly loves Desdemona very much at the beginning of the play and he speaks of her with much affection. He even takes her to Cyprus with him, rather than leaving her at home. She loves him, and is plain about her commitment to him:

"But here's my husband,

And so much duty as my mother showed

To you, preferring you before your father,

So much I challenge that I may profess

Due to the Moor my lord."

Othello actually has no reason to be jealous at any point during the play, but Iago's cunning manipulation plays on his insecurities. The handkerchief is set up as a deliberate plot to stir up trouble between Othello, Desdemona and Cassio. Othello is led to believe in the truth of his wife's infidelity through her hand holding with Cassio when they arrived, to her speaking to Othello on his behalf when Othello has turned him out of his position for his drunken brawl.

Othello is too trusting of Iago and is too slow to see the truth. Had he not been so impulsive and so quick to assume the worse, Iago would have failed. His jealous rage made him kill Desdemona, and then he was unable to live with himself once he realised the truth.

As to whether he deserved his fate or not, many people would blame events on Iago. Without question, Iago is the one who controls most of what happens for his own ends during the play. However, Othello himself has to accept some of the responsibility. He is not a total innocent like Desdemona, and he allowed Iago to manipulate him into jealousy of Desdemona and Cassio.