A novel that's all premise, no plot

Nearly finished with the short novel "The Housekeeper and the Professor," by Yoko Ogawa - strikes me that this is a novel that's all premise. The entire scope of the novel is set forth in the opening pages, and initially it's intriguing and promising: the relations between the housekeeper (single mom in her 40s), the math professor (injured in a car accident and has no longterm memory), and housekeeper's 10-year-old son, whom the professor immediately likes. After that, what? Honestly, nothing happens or changes (30 pages shy of the conclusion), other than little episodes (boy cuts his hand, visit to baseball game, professor gets sick, housekeeper fired by evil sister-in-law but later returns). In most novels, we see relationships grow or develop: for example, perhaps prof is reluctant to let young boy into his household but learns to love him, or, perhaps boy is afraid of peculiar elderly man but learns tolerance. I know those sound sappy - but they're something. So the novel is all premise, but, on the other hand: what does Ogawa do with her premise? The old man has no longterm memory, so every day it's as if he meets housekeeper and son for the first time. Right? But we never really see this happen. The novel moves along as if they're old pals. Similarly, time seems to have stopped for him at his accident (18 years previous), in that he is sure that baseball stars of the past are still playing. But how does this affect his life? He goes outside - is he overwhelmed by technology, by changes? We never know. It's almost as if the novel could be exactly the same if the professor were simply an old man with no dementia.