Um, there is already a non-fiction book detailing the interview answers of a rental stranger called 'Rental Person Who Does Nothing.' This concept already exists in real life, from young Chinese women renting 'boyfriends' to stem the intrusive questions during Chinese New Year gatherings to 'grandparents' being rented in Japan. What it says about our society, the commodification of familial connection, its ramifications as well as the epidemic widespread loneliness is not addressed adequately in this fiction novel.

No sane mother would allow her prepubescent daughter to be picked up at school and spend hours alone with a male stranger. I don't understand the rationale behind employing a stranger to masquerade as the daughter's father long term, the kid or teenager (depending on when she finds out) is going to be so messed up. Not to mention the rental stranger's odd delusions of integrating himself for real into the family. 
I am also confused about the mother's financial situation, she is a single mother struggling to make ends meet and yet has money to rent this stranger for weekly services for a decade?! The rental stranger seems to be more well off than her.
There are odd judgy calls on which clients he is willing to go out on a limb for, based on his internal moralistic sanctimony in spite of his own made-up arbitrary 'rules.' The whole book comes across as working class people = good, decent, hardworking in contrast to wealthy people = jerks, 'rapacious', undeserving of any compassion, perhaps at best to be pitied due to their empty lives.

I need to stop reading books by twenty something year old authors, they regard someone in their mid-fifties as ancient.  Didn't like the protagonist much, going on and on how 'professional' he was and coming to the conclusion that

his mother who committed suicide was selfish and only thinking of herself. It's a desperate act. The rental stranger's mother is her own person.  What her hopes and aspirations are, her anguish is unknown because we only know her through the limited self-absorbed lens of the son.  His closure epiphany on her is a slap in the face to mental health sufferers.  He of course is traumatized too but is shown simplistically as being emotionally stunted and afraid of the dark. Like I said, it takes a more mature author to tackle complex issues like these but many write trauma like a shorthand/emotional shortcut.