Brideshead Revisited Theme of Youth

Youth is repeatedly referred to as "Arcadia," or heaven, in Brideshead Revisited. The novel is told as the recollection of a middle-aged man, so it may well be that a pair of rose-colored glasses is tainting the vision. Nevertheless, youth is presented in all the hazy splendor of a lovely, eternal dream. From lazy days drinking champagne to long strolls in gardens to narrator’s first, eye-opening introduction to a world of art and architecture, there’s little to dislike in this Arcadian paradise.

1. Is "Arcadia" the right term for Charles’s summer at Brideshead with Sebastian? Or is this a rose-colored glasses thing for the middle-aged Captain of infantry, as he calls himself?
2. Speaking of, Charles again refers to his age in the novel’s epilogue, when he calls himself "homeless, child-less, middle-aged, loveless." Is it his age that upsets him so much, or his circumstance?
3. While Charles is in South America, he claims that he "remained unchanged, still a small part of [him] pretending to be whole." What makes him feel incomplete? What is he missing and what does he need in order to be whole?

Charles and Sebastian’s friendship was dependent on youth and could not exist once they both became adults.