This is where you get to play. Fool around. Insert a private joke. This is the no-sweat zone. All you have to do is show your reader around the world the two of you have entered.
Though I suppose I should mention here, before I go on, that not all stories have middles, or the middle is so undefined it’s hard to separate it from the beginning and the end. In Irwin Shaw’s compressed “Girls in Their Summer Dresses,” a man and woman — a married couple — discuss fidelity. She is in favor of it. He is uncertain he can be faithful for life.
They are walking together, down Fifth Avenue, on a sunny November day, but as the conversation develops, a gap opens between them. A crevasse. A tectonic plate. Side by side as they are, there is nevertheless between them a gulf like an earthquake. More… “Daydreams in Dresses”