Here's why:
* The book is written in a humorous, light-hearted style, emphasizing the comedic aspects of dog ownership. While John Grogan's experience with Marley is real, the book exaggerates some events for comedic effect.
* Some events in the book are fictionalized. While the core of the story is based on real experiences, some elements, like certain dog-related incidents, are likely embellished for storytelling purposes.
* The author himself has acknowledged some embellishment. In interviews, Grogan has admitted to altering some details for the sake of the narrative.
So, while Marley & Me is inspired by Grogan's real life experiences, it's not a completely accurate, factual account. It's a story that uses real experiences as a springboard for a humorous and heartwarming narrative.