Othello is unable to understand the subtle nature of love and emotional manipulation -- even to his dying breath he says he is not jealous.
Yet because of his commendable, military service and valor, he is able to win Desdemona and win the respect of the white city leaders who allow him to marry her, despite the resistance of her father.
In this, William Shakespeare's "Othello" is a perfect tragedy.
It is of an extraordinary man whose tragically great nature is both the making of him, and his undoing.
But because of Othello's gullibility because of his hypersensitivity to race and class (and age), due to his background, and his tendency as a career military officer to believe a fellow soldier like Iago more than his own wife, he is undone and kills the person who loves him most, perhaps the only woman who ever loved him.
The racism that has affected Othello's psyche is evident in Othello's society early on, when Iago raises Desdemona's father, Brabatino, to rally support against Othello's marriage surreptitiously.
This paradox gives the tragedy of "Othello" its moral complexity, its instructive power, and its ability to inspire pity and terror.
Most individuals have felt jealousy and suffered prejudice, in one form or another, but Othello's greatness makes him suffer on an epic scale in a way that instructs the viewer that even greatness does not make one immune to cruelty in love.
Also he does not like the fact that Othello is of different race than he is.
Another quote that shows Iago wants to ruin Othello is in Act 1 scene 1 line(s)4-42 “[S’blood,]but you’ll not hear me ....