This was pretty good don't get me wrong and would probably be higher rated if it fit the genre better. The "thriller" genre though is very loose in this novel. This is a fantastic dive into grief and realizing after you lose someone that you didn't know them as well as you would like.
However that dive into grief and loss and realization doesn't give nail-biting like you expect from a thriller. There is a bit of suspense woven in in the form of her father's death being suspicious and while that could be part of a thriller, it doesn't quite keep the thriller genre afloat for me.
So in my opinion this is good if you want a literary novel exploring grief, secrets and a bit of mystery but not a thrill.