improvement in his situation and he is frustrated at Iago's apparent delay. He tells him in Act 4, scene 2:

I do not find that thou dealest justly with me.

When Iago asks him why he makes this accusation, he says:

Every day thou daffest me with some device, Iago;
and rather, as it seems to me now, keepest from me
all conveniency than suppliest me with the least
advantage of hope. I will indeed no longer endure
it, nor am I yet persuaded to put up in peace what
already I have foolishly suffered.

Roderigo is clearly upset and tells Iago that he provides him with some kind of story or scheme but that it appears to him as if he is, in fact, keeping him from achieving his goal, which is to be with Desdemona. He tells Iago that he will no longer stand for it and he is not convinced enough about Iago's intentions. He is also not prepared to easily let go of what he has already foolishly given up and endured.

He, furthermore, tells Iago that he has already heard too much from him since his words and his actions don't match - i.e. he does not put his words into action. He also accuses Iago of having spent all his money and jewels and that he has bankrupted himself, yet, he has received no reward. Iago had received enough money and jewels from him to corrupt a politician and had promised that he had given the same to Desdemona. In return, Roderigo would receive attention and respect from Desdemona, but he had received nothing.

When Iago expresses his disapproval of Roderigo's accusations and tells him to be gone, he tells him that he cannot and will not go. He threatens Iago that he will confess what he has done to Desdemona and reclaim all his jewels. If he is not satisfied in this, he will seek restitution from Iago. 

Iago cleverly manipulates Roderigo by sweet talking him and saying that he recognizes true courage, purpose, and valour in him. He tells Roderigo that if he commits to one more action, he will truly have Desdemona for himself the next night or he could take his life, if not.

The gullible Roderigo is appeased and agrees to prevent Cassio to take Othello's place when he supposedly leaves for Mauritania. If Cassio is not fit to replace Othello, the general will have to stay in Cyprus and so too will Desdemona. And so, once again, Roderigo is manipulated and becomes Iago's convenient puppet.

In the end, though, it is Roderigo's damning letters, found on his person after he has been killed by Iago, that condemns the master schemer and exposes him for a fraud, a malicious liar, and a remorseless cheat.

Roderigo hates Othello because he has won Desdemona away from him.

In fact, Roderigo has even paid Iago to help him in his pursuit of this woman he loves. In Act I, Scene 1, Roderigo learns from Iago that Desdemona has run away from her home to be with Othello, and he is enraged because Iago has failed him, especially after he has paid him handsomely to assist him in winning Desdemona's love.

....I take it much unkindly
That thou, Iago, who hast had my purse
As if the strings were thine, shouldst know of this. (1.1.1-3)

This initial act of treachery by Iago introduces the duplicity of Iago. But, despite this treachery of Iago, the foolish Roderigo is easily enlisted in Iago's plan of revenge against Othello as Iago then assures the gullible Roderigo that he hates Othello, and they should both go to the home of Desdemona's father, Brabantio in order to inform him that Desdemona has left home. Roderigo goes along with Iago perhaps in order to have some satisfaction in enraging Desdemona's father against Othello. Sadly, however, he remains Iago's dupe and is later murdered by this villain.

Jealousy, or "the green-eyed god" as Iago calls it, is Roderigo's chief motivation for hating Othello. There's also more than a hint of injured pride in Roderigo's feelings. He'd been assiduously courting Desdemona for quite some time, even going so far as to pay Iago to help him secure her hand in marriage. But all to no avail. Not only has Roderigo lost Desdemona, he's also wasted his money on Iago's worthless mediation.

Unfortunately, Roderigo is hardly the most intelligent of characters, and his general stupidity, combined with the tempestuous passions of unrequited love, is a dangerous mix indeed. In such a weak and vulnerable state, Roderigo is easy prey for Iago, who cunningly embroils him in his own dastardly plan to settle scores with Othello.

As Roderigo is so foolish, he cannot learn from his mistakes. He thought that lavishing money and gifts on Desdemona would win her round. It didn't. He then thought that perhaps paying Iago to act as a go-between might somehow do the trick. But that didn't work either. And yet here he is again, so lovesick and desperate for revenge, that he's prepared to allow himself to be the pawn of a thoroughgoing blackguard like Iago. This is a man constitutionally incapable of learning his lesson.

There is also more than an element of self-loathing in Roderigo's hatred of Othello. He's everything that Roderigo is not––brave, intelligent and good-looking. Roderigo projects all his insecurities onto Othello in the unspoken belief that, if he can get rid of the "moor" and be with Desdemona, then he will gain a position of respect as well as being able to respect himself.

Sadly for Roderigo, he is much too foolish, dissolute, and immature to realize the utter folly of such deluded fantasies. And although some semblance of wisdom finally does come to the impetuous young aristocrat, it's too little, too late, arriving only after Roderigo has been literally and figuratively stabbed in the back by the wicked Iago. It's something of a tragedy that Roderigo was never able to heed Iago's own advice to Othello in Act III Scene III:

"Oh, beware, my lord, of jealousy!

It is the green-eyed monster which doth mock

The meat it feeds on."

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.

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.