Great idea, flawed execution

I have conflicted feelings about Hello Beautiful, so let's unpack what it is trying to do.

Hello Beautiful starts out with William Waters, who grows up in a home haunted by the memory of his sister who died days after he was born and so his parents were incapable of loving him. When he moves to Chicago for college, he meets and falls in love with Julia Padavona. But Julia comes with her large, loud, and complicated family. A bossy mother (Rose) with greater expectations than many people can live up to, a loving father (Charlie) who pretends to be incapable at doing much but whose care and love for poetry touches many in the community, and her three younger sisters Sylvie, Cecilia, and Emeline.
It's the late seventies and William is clueless about what to do with his life after an injury keeps him from pursuing the sport he loves (basketball). So he and Julia rush into a marriage because William needs a saviour and Julia needs a project.
However, it is on the eve of their wedding that the seemingly perfect Padavano family starts to fall apart, as the youngest daughter, Cecilia, turns up pregnant out of wedlock and is promptly kicked out and disowned by their mother. Julia tries to keep her family together by also getting pregnant, but when Cecilia gives birth to her daughter Izzy, Charlie dies and Rose promptly abandons her daughters to go live in Florida. From then on it is a downward spiral.
William is trapped in a postgraduate degree he is unsure he wants to do and incredibly frightened by the fast approaching reality of him being a father because as his sister died and his parents screwed him up, he is afraid of repeating the pattern. Julia in her turn is increasingly disappointed in the lack of ambition in her husband and pulls back.
Till one evening when William walks out of their apartment, files for divorce, and then attempts to give up his life-subscription.
Julia is properly shocked by this (Cecilia also says some god-awful stuff about it but she is genuinely not important at this point in the story) and takes her newborn Alice (there are so many women in this book and still the main character are men??) and runs away to New York to become a Business WomanTM.
While William recovers from his attempt, his closest confidante becomes Sylvie who in him recognises the spirit of a tortured poet (cue Taylor Swift). They (almost predictably) fall in love and when word of this reaches Julia (who is now officially divorced from William and Alice's only legal guardian) she blows up and cuts off all communication with the rest of her family.
The last 100(?) pages of the novel are dedicated to Alice growing up and then Sylvie getting c*nc*r and d*ing. This brings the entire family back to Chicago and familial ties are starting to be reconnected in the last fifteen pages.

I think the book sets up a good enough premise. The idea of sisters which were once close and then are driven apart and their later attempts at reconnecting sounds like a wonderful mixture of sweet and painful. But I feel like Hello Beautiful cannot deliver what it wants to do. The ending felt rushed and the fact that Sylvie got sick and passed in such short progression made it almost unbelievable. I also think that William did not reflect half as much as he could on the crucial role he played in the familial rift. Just as there were consequences to his actions (and yes, while we should always understand the context of being mentally ill and what that does to people's behaviour, we can still try and hold ourselves and others responsible to at least some degree), he gets away nearly scott-free and the POV shifts to Alice and Sylvie, after which we just get more of the same confusion haunting Alice as haunted her father, without there ever being a satisfying conclusion to how you are then supposed to live. The last sentence may allude to "together", but I'm not sold on the argument.

I read someone say that this book is anti-eldest propaganda, as they, as the eldest, felt attacked by this book. As another family's eldest daughter, I don't agree. I can sort of understand Julia, but in the way that Ann Napolitano's characters can be understood in a more general sense; I can also understand a 2D drawing of a cube.
I think that is the problem I have with Ann Napolitano's writing in general. I also read Hello Edward and I want to love the books! I do! The ideas are so good! They could be great explorations of the human condition and the relations with whom we cherish most. And then every time that one of her books gets semi-close to actually touching on some sincere thing, it ends? It swerves away? And I think that is a shame.

Yeah, overall; good research question, the execution of the research leaves much to be desired. It's a passing grade for me fam.