What role did suspicion and mistrust play between Othello and Desdemona?

Answer:  Though Othello was black complexioned Moor, Desdemona loved him and they married each other secretly and later, her father approved of the marriage. But Iago became furious and jealousy when Othello promoted Cassio to the post of Lieutenant and being more experienced and senior to Cassio, Iago deserved that post. To take revenge against both of them, Iago planned a plot of false military riot and blamed Cassio totally for it. As a result, Othello removed him from his post. Later, Iago planted the seeds of suspicion in his mind that his wife Desdemona had illicit love-affair with Cassio. Iago, with the help of his wife, stole a handkerchief of Desdemona and informed Othello that he had seen Cassio to use that handkerchief which was a token of their love. When Desdemona could not show the handkerchief, Othello became furious and accused her of infidelity and finally killed her out of mistrust and suspicion. Later on, when Othello realized that Desdemona was innocent, he also killed himself. Thus, suspicion and mistrust brought tragedy in the main story.