"It was fun, fun day at work," Zellweger tells PEOPLE
Credit: Matthew Eisman/Getty Images

There may be a love triangle in Bridget Jones’s Baby, but Renée Zellweger reveals the real romance was off-screen between her male costars Patrick Dempsey and Colin Firth.

“I saw a bromance between Colin and Patrick. I tell you,” Zellweger told PEOPLE at the New York premiere for the film.

“Fast friends. Mutual respect. Lots to talk about it was fun, fun day at work,” she added.

In the third installment of the Bridget Jones franchise, Zellweger, who returns as the titular character, finds herself in her 40s and dealing with a dilemma after finding out she’s having either longtime beau Mark Darcy (Firth) or new flame Jack Qwant’s (Dempsey) baby.

On wearing a prosthetic bump for the role, the actress admitted she now empathizes with pregnant women.

RELATED VIDEO: Patrick Dempsey Talks Working with Renée Zellweger in Bridget Jones’s Baby

“It was hot and heavy and didn’t smell very nice. But I got to take it off at the end of the day unlike the ladies who were having the real experience,” Zellweger shared. “So I can not complain. It really did make the experience more authentic, because my feet did bother me. You did feel it.”

Bridget Jones’s Baby hits theaters Sept. 16.