Breaking Away From the Maternal and Material
Jack's plight throughout the film can be seen as the journey of a boy who has grown up without a father. Throughout Fight Club, Jack searches for an authority figure to show him the path toward manhood, what to truly strive for, and the path toward these goals. We hear him often repeat, "what's next?", implying that Jack has not yet found what it means to be a man.
Jack's life is filled with the traditions passed on to him, where the path to drown out who you are and forget about your existential problems lies in the structure of schooling, work, and marriage. This is the goal that Jack has been taught to strive toward, and his journey is a spiritual journey, as he discovers that it is the path to nowhere. Jack, despite being 30, is still seen symbolically as living under the maternal influence. The way he sleeps is symbolic of a boy sucking on his thumb; his surroundings are a symbolic gesture of maternal comfort; his symbolic father is his boss; the firm he works for is the family that feeds him; and his house, which he furnishes with feminine accoutrements, is the womb. Jack is lonely, as he realizes that the material objects which he has been taught hold primacy, are unable to replace the void of relationships and his own masculine inadequacy.
We see that his discontentment with life manifests in the form of suicidal ideation and insomnia. As a product of society whose ultimate goal is to maximize happiness and minimize pain, Jack seeks a prescription to numb himself, hoping to stunt any potential for growth which requires pain. Bob's breasts are further symbolic of Jack's inability to break away from the maternal tether holding him back. The film makes allusions to castration, with the basketballs around Jack during his meeting attendance, the scene where Tyler threatens to castrate the man, as well as Jack's own encounter with the detectives. This indicates to the audience that Jack does not see himself as a man, but as a boy ("I am six years old again," and "I can never get married").
Upon Tyler's arrival, Jack goes through a ritual, transitioning from a state of boyhood entering manhood. This is symbolized as his apartment blows up, removing him from the comfort of the material and maternal. His plight now is to become a man without a father, which he attempts to do through Tyler, his alternate ego. More is revealed, and we see that Jack begins to hate his father, as Tyler tells Jack that he saw his father as a God, but that his God rejected him, and he likely never loved him. He then begins to attribute the pain he feels as being caused by those around him, eventually believing the world is the cause of this pain (terrorist organization).
If Tyler represents the father figure, then Marla, also a product of Jack's imagination, is the mother figure. The relationship between the three presents the audience with a family dynamic, where the child hates one sex and admires the other. Marla (mother) has chosen Tyler (father), and as a result, discards Jack (son). This is why in the second half of the film, Jack turns against Tyler, his metaphorical father, and ends up killing him.
And so, what we see toward the film's end is that Jack, absent Tyler's presence, must assume Tyler's role. He must become the father that Tyler was to Jack. One of the themes here, it seems, is that children, growing up without male influence, eventually must grow up and become men; yet without guidance, what kind of men will they become?
The final moment has Jack metaphorically/physically killing himself, indicating that the de facto father (Tyler, television, mother) is an insufficient and ultimately destructive surrogate.