What does Gavin Casalegno think is to come for Jeremiah’s love life in The Summer I Turned Pretty movie?

In the season 3 finale of the hit Prime Video series, the younger Fisher brother started up a fling with Denise (Isabella Briggs), a work friend whom he’d been living with in Boston.

The kiss between Jeremiah and Denise seemed to throw both of them off, but was also a natural segue after Denise lauded her roommate as a “10” and encouraged him to stop comparing himself to Conrad (Christopher Briney).

Now that there’s a continuation locked down for the characters — Prime Video confirmed that the story will officially conclude with a movie, which author Jenny Han will direct and write, alongside her co-showrunner, Sarah Kucserka — there’s also a question of what Jeremiah and Denise’s future might look like in the next installment.

“That’s a good question,” Casalegno, 26, tells PEOPLE about whether Denise could make a return in the movie. “I don’t know if I’ve thought too much about [that].”

“I think it’s a little early for Jeremiah to be jumping back into a relationship,” Casalegno admits, referring to his engagement to Belly (Lola Tung) and their almost-wedding.

“Obviously, they’ve been living together for a little bit, and you learn — you spend a lot of time with [that] person, but genuinely, I think it might be too early for that.”

“But who knows?” Casalegno quips. “I don’t write it, so I don’t know.”

The romance between the former co-workers was definitely a surprise for Casalegno, who says he did not see that coming whatsoever.

“When I got the script where things were starting to switch, actually, [Han] told me it was coming [around] episode six, and I was like, ‘Holy frig,'” he recalls. “I did not see it coming.”

“But it was so great,” he adds of their moment in the finale. “Yeah, that was a curveball for me, too. It was fun. It was good.”

Sean Kaufman, who plays Steven and initially tried to explore a romantic connection with Denise earlier this season, was not as surprised by the twist. “I think I knew pretty early on,” he tells PEOPLE.

While his focus was more on Steven and Taylor (Rain Spencer) being endgame — “My hope always was that Steven and Taylor end up together, by the end of the season,” he says — Kaufman, 25, says that some seeds were sown in earlier episodes for Jeremiah and Denise’s ending.

“While we were shooting some of those office scenes earlier in the season, there were just sometimes certain lines and certain stuff that I think fans will look back on and realize — there’s kind of a vibe,” he reveals. “I think they kind of skipped over it, which I think is the point, but looking back on it, there’s certain stuff that.”