caption above says, "he used to wait for her to get off work."
this work shows two couples sitting in a sushi bar, with the lady pouring the guy a drink in the foreground.
in most cases, when something is in the foreground, it usually is the main subject of a painting/ drawing. however, when you look around the cup, you will notice a pair of legs outside of the restaurant, behind the hanging cloth. Thats the main focus on this cup, and also why the piece is titled, "wait".
the main Subject here though, is his ex, who isnt in the picture. literally. hence "he used to wait for her.."