Nick is the omniscient narrator which means that he sees everything that is going on and the way that he does this is by accumulating as much information as he can from as many people / characters as he can. Nick tells the reader that he is one of the most honest people that he knows or has ever met but, at the same time, his truthfulness depends upon how truthful the information that he receives is. If Nick passes on false information, it is probably due to the fact that he got the information from unreliable sources. For example, everything that Nick knows about Gatsby, up to the point when Gatsby’s father comes into the novel, is a complete fabrication because he is being lied to or given false information.
As for the other two characters – Daisy lies mostly to make herself feel better about her own life because it is clear that she is unhappy and Gatsby lies because he must in order to keep up the false life that he has created for himself in order to eventually get to Daisy.
in what way is gatsby's uniform an invisble cloak"?