what haunting feeling does nick sometimes have? what does his description of his feelings and the indication that others feel this way say about american society or life in the city at the time?

Nick feels this strong sense of loneliness even amidst the lavish parties and high society of East Egg. This is because Fitzgerald defines these people as superficial and largely incapable of forming meaningful relationships. Indeed many of them have forgotten what it is to care for someone other than themselves. Nick is an "outsider" in this society and often struggles to cling to the values of his middle class upbringing. The rest of East Egg society are desperately lonely too but don't or can't comprehend it in the same way as Nick,

"...I felt a haunting loneliness sometimes, and felt it in others - poor young clerks who loitered in front of windows waiting untilit was time for a solitary restaurant dinner - young clerks in the dusk, wasting the most poignant moments of night and life."