Othello: A Possible Flaw in the Plan

Iago apparently has everyone convinced of his saintly personality, everyone besides Roderigo.  Roderigo is angered at Iago because he had been promised that Desdemona would become bored of Othello and fall in love with him, but he hasn't seen any improvements in this area. Furthermore, Roderigo has been giving Iago jewels to give to Desdemona as tokens of his affections, and  now doubts that Iago has even given these to Desdemona. Roderigo says, "I have heard too much, and your words and performances are no kin together." (IV.ii.181-182). He continues, "I tell you ’tis not very well. I will make myself known to Desdemona. If she will return me my jewels I will give over my suit and repent my unlawful solicitation. If not, assure yourself I will seek satisfaction of you." (IV.ii.190-194).  It seems to me that Roderigo might possibly be the hiccup in Iago's plan that I have been anticipating.  With plan as intricate as Iago's, I would be amazed if absolutly nothing went wrong. However, Othello is one of Shakespeare's tragedies, so the likelihood of the villain being successful is far greater.