Bowed by the weight of tragedy, Old Mrs. Karafilis does not understand why Americans pretend to be happy all the time. To her, the suburbs are a place where artificially manufactured surroundings and lives culminate in the tyranny of an enforced happiness. Rather than indicating one's personal feeling, suburban happiness is instead a matter of social ritual, a process by which the community continuously and collectively reaffirms itself. For Old Mrs. Karafilis, this hypocrisy is typified by the figure of Mr. Lisbon stringing Christmas lights despite his daughter's recent suicide.
The novel's sociological exploration of suburban ritual supports Old Mrs. Karafilis' theory. The high school holds a day of grieving in response to Cecilia's death, which the school considers to be a great success despite the fact that the suicide was never mentioned and that the Lisbon sisters wait out the day in the bathroom. The neighborhood fathers remove the particular fence on which Cecilia jumped, giving no thought to the other fences in the neighborhood. The Parks Department systematically removes all the neighborhood trees in the name of saving them. These examples describe a widespread suburban emphasis on form, ritual, and propriety over and above content. What is proper is infinitely better than what is morally or humanly appropriate, and the latter are readily sacrificed for the former. In this infrastructure of charade and self- destruction, the forgery of happiness is another necessary farce.
The deep irony of American happiness is suggested by the characters of Lux Lisbon and Trip Fontaine. After living his youth at the pinnacle of the American dream, Trip spends his middle age in detox recovering. Likewise, Lux's decadent sexuality culminates in her premature death. Trip and Lux's search for love and happiness takes a sharp toll on their bodies; similarly, the suburban attempts at American happiness prove false, fickle, and fatal.
Written to make sense of a great loss—the death of the Lisbon sisters—the novel is continually concerned with the progressive deterioration of the little life that has remained. The twenty years that have passed since the girls' suicides have affected the boys' precious archive of the girls' lives. Bras, makeup, photographs, tennis shoes, candles, and other trinkets have begun to stiffen, yellow, disintegrate, and fade. This physical deterioration parallels the gradual disintegration of the boys' memories, mental images, and sensory recollection of the sisters. Furthermore, the boys are aware that both artifact and memory are becoming less potent. Where a photograph might once have sparked an immediate surge of memory, it now takes minutes of concentration for the boys to conjure a similar response.
In many ways, the inexorable decay of what remains is more devastating than the initial loss. The boys' only consolation against the immense void left by the Lisbon suicides is their project of "putting the girls back together," or reassembling their lives, motives, visions, and dreams from the pieces they left behind. The boys' are unable to appropriately recreate the girls' lives. Their despair at failing to do so is exacerbated by the knowledge that each day that they fail, they have less knowledge, less evidence, and fewer memories to try again. In exploring this slow decay, the novel hints that tragedy need not be spectacular to be devastating, and contrasts the sudden loss of the Lisbon sisters' lives against the boys' own slow descent to death.