Othello is mad at Cassio because he is "hitting" on his wife but he is only trying to get his job back because he got drunk and got into that fight where hi stabed someone.
"I am bound to thee forever" Othello (pg.133) he is talking about how is is still in love with his wife but he is thinking about killing or leving her because he is thinking that she is cheating on him with cassio. " Villain, be sure thou prove my love a whore!" (pg.143) It is when he is talking to Igao about his wife and Cassio cheanting on him. With othello in act 3 it is all about trying to find out if hs wife is cheating on him.
