Colleen Hoover is clearing the air.

At Book Bonanza, theNew York Timesbestselling author’s annual book festival, Hoover spoke about the upcomingmovie adaptation ofIt Ends With Us— and addressed some of the controversy surrounding the film.

The movie is based on Hoover’s 2016 novel of the same name, which, according to asynopsis on her website, follows Lily, a recent college graduate who moves to Boston and falls in love with Ryle, a neurosurgeon with a “no dating” rule. As the two grow closer, Lily’s first love, Atlas, comes back into her life and threatens what they have built.

Sean Zanni/Patrick McMullan via Getty, Nancy Rivera / SplashNews.com

SinceannouncingthatBlake LivelyandJustin Baldoniwill play Lily and Ryle in the film on Jan. 26, Hoover has faced backlash because of the significant age discrepancies between the actors and theirIt Ends With Uscharacters.

Lively, 35, is over a decade older than the 23-year-old protagonist. Similarly, Baldoni, who is also directing the book-to-screen adaptation, is nine years older than his 30-year-old book counterpart.

It Ends with Us by Colleen Hoover

Now, five months after their casting, Hoover has an explanation for the age gap.

“Back when I wroteIt Ends With Us, the new adult [genre] was very popular,” she said at the June 23 festival, according toToday. “You were writing college-age characters. That’s what I was contracted to do.”

The author continued, “I didn’t know that neurosurgeons went to school for 50 years. There’s not a 20-something neurosurgeon.”

Hoover viewed the adaptation as an opportunity to remedy her error. “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.”

The author also said she is “extremely happy” with the cast, especially Lively, who Hoover said she has been “obsessed” with since her turn as Serena van der Woodsen onGossip Girl.

Despite this, the self-described pessimist said she hasn’t allowed herself to “get truly excited” about Lively joining the cast — or anything else — because something bad could happen. “It’s not done filming,” Hoover said at the festival, according toToday. “Anything could go wrong.”

Never miss a story — sign up forPEOPLE’s free daily newsletterto stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

As for fans who are, as Hoover phrased it, “upset about outfits and whatnot,” her advice is simply to wait until the film hits theaters.

Though she said she “loves” the costuming conversations thatset photos from the filmgenerated, she had a message for fans: “You’ve seen a couple of outfits that are completely out of context. I’m not worried about it.”

Blake Lively.Splash News

Blake Lively

Splash News

“I don’t remember describing outfits at all,” the author told fans, perToday.“I don’t care what they have on. In my head, it’s about the conversation they’re having and the story.”

And when it comes to the story translating onscreen, Hoover said she was “blown away.”

“I got to see the footage they filmed thus far,” she said, perToday. “I’m not a crier. I know that I write emotional books but I’m not an emotional person. And I cried so much on set.”

Hoover continued, “You guys are going to be so happy. I’m extremely happy and now my expectations are up and I’m going to keep them there.”

source: people.com