Roderigo hates Othello because he was one of the suitors for Desdemona. He is still in love with Desdemona and hates Othello because she chose Othello over him. One can see why Desdemona rejected him because he is so gullible and easily duped. Iago tells Roderigo that Desdemona is only physically attracted to Othello and will soon grow tired of him. Roderigo is the one who informs her father that Desdemona has escaped with Othello, something that would not endear Desdemona to him. Then he becomes a pawn of Iago, mindlessly following every command Iago gives him. For his efforts, he is wounded by Cassio and finally murdered by Iago himself.
As was mentioned in the previous post, Roderigo is the young, gullible Venetian suitor of Desdemona. Roderigo is madly in love with Desdemona, which provides Iago the opportunity to manipulate Roderigo into giving him all of his money in exchange for his help at winning Desdemona's love. Throughout the play, Roderigo becomes jealous of Othello after he learns that he has married Desdemona. Roderigo even contemplates committing suicide after Desdemona marries Othello. It is jealousy that fuels Roderigo's hatred for Othello. He is attracted to Desdemona and feels heartbroken after she chooses Othello to be her husband. In Roderigo's mind, Othello has stolen his true love, and Roderigo is willing to go to extreme lengths to earn Desdemona's love. Later on in the play, Iago convinces Roderigo to fight Cassio after mentioning that Desdemona is attracted to him.