We continued to watch the film, and are very close to the end.
Near the end, when Othello decides he must kill Desdamona for being unfaithful to him, we see that there is an important theme of trust. It is very important to Othello that he trusts the people around him, and if he discovers otherwise, he does not want to deal with the consequences. The idea of love overcomes the idea of mistrust, as Othello kills Desdamona, even though he still loves him.
When Othello finds out the Iago was lying to him about Desdamona being unfaithful, Othello realises that it is Iago who was being the less trustworthy and loyal throughout the time we see. This causes Othello to kill Iago, as it is his fault that Desdamona is now dead.
