The casting of Blake Lively and Justin Baldoni as Lily and Ryle caused backlash from fans because in the book Lily is 23 and Ryle is 30, while Lively is 35 and Baldoni is 39. Author of the book Colleen Hoover explained in an interview that she wanted to age the characters up in the movie in an effort to correct a mistake she made in the book. She said, “Back when I wrote It Ends With Us, the new adult [genre] was very popular. 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 6-12 years. There’s not a 20-something neurosurgeon. As I started making this movie, I’m like, ‘We need to age them out, because I messed up.’ So, that’s my fault.”
