what kind of relationship exists between Nick and the Buchanans in 'The Great Gatsby?'

The relationship was awkward at best before Gatsby's death (remember, Nick was actually somewhat poorer because he lived in the other Egg, and had a small house as well, so he didn't really fit in), but by that time, Nick has an epiphany that the entire culture in which the Buchanans live is totally corrupt. He despises them all in their vanity, and that's why he leaves for his original home. He's especially fed up with the way that Tom orchestrated Gatsby's murder and Mr. Wilson's suicide in order to fulfill his own goals of having Daisy to himself as a trophy wife (and possibly avenging the loss of pleasure he got after Myrtle's death).