How does the past (childhood & nostalgia) affect Nathan Zuckerman in American Pastoral?

In American Pastoral,Nathan Zuckerman has created and cherished a series of romantic myths about Seymour "the Swede" Levov, the brother of his closest friend in school. When he encounters the Swede early in the novel, he feels that something has gone wrong—that the immense promise of the boy who was considered practically a demigod in high school has been compromised or destroyed (even though the Swede has remarried and now evidently leads a normal, happy life).
What Zuckerman knows of the Swede, up to this point, seems to confirm what everyone had expected of Seymour. He was a champion athlete, breaking all the school records in New Jersey. After returning from the service, he married, entered his father's business, and became the owner upon his father's retirement. He then moved out to the suburbs, to Morris County, far from his Jewish working-class roots in old Newark. Yet as the whole story unfolds, Zuckerman finds himself witnessing a Greek tragedy. Perhaps the story would not be so shocking if Zuckerman hadn't created such a deeply mythologized view of the Swede, and of his Newark childhood overall. For Philip Roth, in his Zuckerman persona and elsewhere, old Newark is an Arcadia, a prelapsarian world. It shakes Zuckerman that Seymour Levov, the one person who emerges from this Eden as a hero without a single flaw, is destroyed by circumstances beyond control. It's a testament to the inability of even the most virtuous and gifted person to escape tragedy.
The rebellion of Seymour's daughter Merry, though a shock in the context of the Swede's mythic stature, should not be surprising, of course. The late 1960s and early 70s were a time of vast social upheaval in the US. That Merry first becomes a "terrorist" and then a Jain, withdrawing from reality into a purgatory-like fantasy world, can be partly seen as a result of the Swede's own tragic flaw. Zuckerman's fixation on Seymour and his story stems from Zuckerman's own idealization of the childhood setting he reimagines over and over (as Roth himself does). Yet the Swede seemingly has not grasped, until the final deterioration of his daughter, that the course of his own life may have been wrong in some way. In his case, the marriage to a woman from a different background has backfired. The Swede and his wife create their own fantasy world in the rural setting of Old Rimrock. In spite of Seymour's devotion to the effective management of his father's glove business, by living on a farm he's trying to escape reality—the reality ironically embodied in Newark, where one identified strongly with one's ethnic and religious group and where one's Jewish identity was a prime factor in the direction of one's life. The Swede attempts to create for himself a "new" Eden in the countryside of Morris County, but the result is a catastrophe for him and for his family.