In Hoover’s book, Lily is 23 years old and a recent college graduate when she first meets 30-year-old Ryle.
Her other love interest, Atlas, is described as two-and-a-half years older than her.
But in the film, the characters are played by actors significantly older than them — Lively is 36, Baldoni is 40, and Sklenar is 34.
Hoover has previously said that she “messed up” by making the characters in the book too young.
She has said that her involvement in the movie allowed her to correct her mistake.
“Back when I wrote ‘It Ends With Us,’ the new adult (genre) was very popular,” she said, per Today. “You were writing college-age characters. That’s what I was contracted to do. I made Lily very young. I didn’t know that neurosurgeons went to school for 50 years. There’s not a 20-something neurosurgeon.”