Responses
Considering the "friend?" Was the author and the og story was more on romance the friend most likely based the story setting where they live, since the areas are same the the only thing that probably really changed is the main characters/side characters coming into existence.
That or there's a plot twist of some sort, but that just what I think
he got sucked into the world of the novel right? and he regressed to his 19-year old self? so how come his grandma is there when it's supposed to be set in a different world/universe?