Maybe because the book was non-fiction? Maybe because the very first line of the book was:
"In the year 1908, Pierre Bonnard painted 'The Bathroom' and my mother was born."
That line in and of itself is fine. But what I didn't know was that the whole chapter seemed to be about Pierre Bonnard. Of course, that isn't entirely the case. The author was also introducing her mother as she celebrated her ninetieth birthday. I did catch on quickly that each chapter was about "My Mother and _________" whatever, ie. "My Mother and Her Bosses", "My Mother:Words and Music", "My Mother and Her Sisters", etc., etc. etc.
While in theory this might sound like an interesting way to tell her mother's story, I found it incredibly tedious and boring. And to make things worse, the last chapter was "Bonnard and My Mother's Death". Yes, she finished the book again talking about Pierre Bonnard.
This just was not a book that I could relate to at all, despite the loss of my mother and her dementia.