At the end of Chapter 2 of The Great Gatsby, Nick leaves the party with Mr McKee. While they are in the elevator, Mr McKee invites him to come to lunch some day, and Nick agrees.
And then, after a mysterious "..." in the next paragraph, he is suddenly standing over a half-naked Mr McKee who is showing him his portfolio.
Mr. McKee turned and continued on out the door. Taking my hat from the chandelier, I followed.
"Come to lunch some day," he suggested, as we groaned down in the elevator.
"Keep your hands off the lever," snapped the elevator boy.
"I beg your pardon," said Mr. McKee with dignity, "I didn't know I was touching it."
"All right," I agreed, "I'll be glad to."
. . . I was standing beside his bed and he was sitting up between the sheets, clad in his underwear, with a great portfolio in his hands.
"Beauty and the Beast . . . Loneliness . . . Old Grocery Horse . . . Brook'n Bridge . . . ."
Then I was lying half asleep in the cold lower level of the Pennsylvania Station, staring at the morning TRIBUNE, and waiting for the four o'clock train.
What happened here? Did he invite him to come inside right away, right after inviting him to "come to lunch some day"? Why is this part suddenly glossed over in the narration?
This whole ending feels very strange to me. It is not clear to me if Nick is dreaming this, or imagining this, or what.
I still haven't finished the book so I'd appreciate an answer without spoilers. Moreover, I'm looking for an explanation as to what happened, inside the book. Not for an analysis of this ending. For instance, the fact that, say, the names of the pictures shown somehow represent the evening that Nick's been through, is irrelevant to me.