Why would a book that's heavy on rape be tagged as a romance? It's not mentioned as such on Amazon.
I haven't read the book to see if it's also a romance besides being a thriller, but to see a book where the first few chapters have multiple characters getting raped tagged as a romance definitely raises a red flag for me.
Genres and tags on Goodreads are sourced from how members shelve the book. So in this case, members have shelved the book as romance which is why it's showing up with that genre.
I haven't read the book to see if it's also a romance besides being a thriller, but to see a book where the first few chapters have multiple characters getting raped tagged as a romance definitely raises a red flag for me.