I'm not sure who the author of 'world's best boyfriend novel' is as the name is quite general and there could be many novels with similar themes by different authors.
It's difficult to pinpoint a single best-selling fiction author as it can vary depending on different time periods and regions. However, some authors who have consistently achieved high sales include J.K. Rowling and Dan Brown.
It was difficult to have a definite answer to this question because the best children's literature. However, some famous children's literature such as Andersen, Grimm's Fairy Tales, Dickens, Mickey Mouse, and Donald Duck. These can inspire children's imagination and creativity to help them become thoughtful, emotional, and responsible people.
I don't know who the author of this 'the best thing in the world sight word story' is. There is not enough information just from this title to determine the author.