The film seems, on the face ot it, to be about the return of a prodigal daughter; the teen who sees the error of her ways, tries life out in the big wide world on her own, and comes home because she realizes that the grass is not always greener on the other side of the fence, however attractive and wonderful it seems.
However, just beneath the surface, the film is also about emotions that are not dealt with and the eternal struggle between the generations, especially at a time when there is such a gaping void between the adolescence that the older generation experienced and the one that their daughters are not having.
Dennie felt emotionally constricted at home, which is why she was attracted to the freedom that the hippie colony offered. Ironically, her boyfriend is extremely controlling and so leaving her parental home for her new hippie one does not really give the personal freedom that she had been looking for, and her life is still essentially controlled by someone else. She does not fare well living on her own and comes home, the trade off with her parents being their immediate, no-questions-asked acceptance in exchange for her conforming to the Stepford daughter image that have of what their child should be like.
Suppressing her emotions is not easy and she finds it increasingly impossible to do. At first she reacts to stress by jumping in the pool fully clothed and swimming laps, to try to physically calm herself down, but she ultimately deals with her emotions by not having any, and at the end of the film we see her vacuuming the house with no expression on her face at all.
