The central character and theme in The Death of the Heart

It's taking me a while - Elizabeth Bowen doesn't make it easy for her readers - to get to the "heart" of The Death of the Heart (1938), but now reading the 2nd of three sections the focus of the novel becomes more clear. The novel opens with a lengthy account of the trials and tribs of the Quayne family, as told, to a friend, by Anna Q., who recounts her husband's family, the 2nd marriage of his father (after he got his 2nd-wife-to-be pregnant), the birth of their daughter, and the death of both parents. Throughout this narration and through most of the first section I felt I had no sympathy for and little interest in Anna, her husband (Thomas?), and their entourage - privileged people in the finest of London neighborhoods with a litany of complaints about servants, hangers-on, and most of all Thomas's half-sister, Portia, who keeps her room a mess, is in and out at all hours, is indifferent to her schooling (finishing school, we would say today), and keeps a diary about which Anna, that snoop, is put off by what Portia says about, observes of the Q family. By the 2nd, section, however, I have come to see that this novel is really about Portia and her mistreatment: She's a 16-year-old girl, orphaned, sent to live in London, where she's never been, with her brother and his wife, whom she hardly knows - and she's treated w/ cruel neglect. Anna and Thomas go off to spend the xmas holidays in France, but do they even consider bringing Portia w/ them? No, they find a place - basically, the home of the woman who was a servant in Th's family when he was a child, where they can stash Portia away for a few weeks, or maybe longer. She obviously feels like a boarder there - we're not in Dickens territory by any means, but Portia certainly feels abandoned and neglected and unwanted - as well as confused by her first glimpse of life in a crass, difficult family, For all her troubles, she's been sheltered and she knows little about the world. The only person who seems interested in her is Eddie, a 23-year-old guy who works for Thomas and is hitting on Portia with no obvious good intention or concern for her welfare. For reasons obscure to me, she gives him her diary for safekeeping; Bowen gives us a few pages of her extremely mundane diary, which contains no scary revelations. She's just a lonely kid, a stray whom nobody really wants to take in; her fate will be the fate of this novel.