For a three-act plot analysis, put on your screenwriter’s hat. Moviemakers know the formula well: at the end of Act One, the main character is drawn in completely to a conflict. During Act Two, she is farthest away from her goals. At the end of Act Three, the story is resolved.
Simply put, there is just no action in this story. The protagonist doesn't do anything, nor do the other two characters. Basically, we have three guys who represent different stages of life – the story is more of a meditation on these stages than an actual "story" about any one of them. After all, even though the older waiter is singled out as the character we get to "know" the best (since we see his thoughts), he doesn't commit to any course of action – the point is, after a certain age, there is no action left to take.