Colleen Hoover reacts to 'It Ends With Us' movie casting age discrepancies: 'I messed up'

Colleen Hoover finally spoke out about fans' concerns that she casted actors who were too old to play her two main characters, Lily Bloom and Ryle - and admits that she "messed up" in the process of the creation of the story.

In case you missed it, Colleen Hoover was under fire from her fans for the past few months because of who she decided to cast for the upcoming and highly-anticipated It Ends With Us movie. 

The author decided to cast Blake Lively, 35, as her protagonist Lily Bloom, who is supposed to be 23 years old in the book. Similarly, she cast Justin Baldoni, 39, as Ryle, who is supposed to be 30. Fans were concerned once the casting choice was made that these two actors were too old to play the part - and that concern only increased once behind the scenes photos of filming were released of Blake (with her dramatic red hair transformation) and Justin on set. 

Recently, while speaking with TODAY, Colleen revealed why she chose to cast Lily and Ryle older - and it's for a practical purpose. 

"Back when I wrote 'It Ends With Us,' the new adult (genre) was very popular. You were writing college-age characters," she said. "That's what I was contracted to do. I made Lily very young. I didn't now that neurosurgeons went to school for 50 years. There's not a 20-something neurosurgeon."

She then continued that the movie served as an opportunity for her to correct that mistake. "As I started making this movie, I'm like, we need to age them out, because I messed up," she said. "So that's my fault."

Colleen says that, despite the backlash from fans, she's really excited to have Blake in the role - and is still in disbelief that the Gossip Girl actress accepted the role. 

"I was like, ''Yeah, okay, that'd be great.' I think (Baldoni) expected (me) to just scream into the phone," she started. "But he doesn't realize ... I have not allowed myself to get truly excited because I'm like, something could happen. It's not done filming. Anything could go wrong," she said.

She also noted that, when she writes her characters, she doesn't really think of what they look like physically - so casting Justin and Blake was a huge treat for her, considering she never gave much thought to the details of what those characters would look like physically. 

"I don’t really picture characters in my head as I write. It's more of a personality thing. I picture like borders and then who they are inside," she said.