Modern Interpretation would say that Othello's tragic flaw was that he had internalised, that is taken into himself, the prejudices of those who surrounded him. In his heart he had come to believe what they believed: that a black man is an unattractive creature, not quite human, unworthy of love. Thinking this, he could not believe that Desdemona could truly love him for himself. Her love must be a pretense, or a flawed and corrupted emotion. Iago hinted these ideas and Othello rushed to accept them because they echoed his deepest fear and insecurities.