As he set out on “The Worst Person in the World,” which premiered July 8 in competition at Cannes, director Joachim Trier wasn’t looking to expand what he informally calls the Oslo Trilogy.

Having worked stateside with 2015’s “Louder Than Bombs” and in genre with 2017’s “Thelma,” the Norwegian filmmaker just felt the need for a kind of soft reset.

“My co-writer Eskil [Vogt] and I wanted to go back to basics, back to the form we started out with — human stories, in this case about love,” Trier said. “And to embrace that sense of playfulness and musicality we had in previous films.

“But as we finished the script, and saw that [“Reprise” and “Oslo, August 31st” star Anders Danielsen Lie] and the city of Oslo would play major roles, we realized it would connect. We said, “Let’s not feel ashamed, let’s feel free to embrace this label as well.”

Reuniting Trier’s usual band of collaborators, the film shines the spotlight on lead actress Renate Reinsve, a rising talent in the Norwegian scene who had taken a bit part in “Oslo, August 31st.”

“She had one line of dialogue but we actually [worked on set for nine days],” the filmmaker explained. “She hadn’t really gotten a lead before, so we brought her in and developed the character together.”

Assuming a novelistic form of twelve chapters sandwiched between a prologue and epilogue, “The Worst Person in the World” follows late twentysomething Julie (Reinsve) over the course of several years and romantic entanglements — among them a long-term relationship with a cartoonist played by Anders Danielsen Lie — and works as a kind of millennial bildungsroman for a generation still looking for stable ground.

“It’s a coming of age tale for grown-ups who wish they had already done so,” Trier said. “While the classic coming-of-age novel would follow someone in their late teens, this is about someone who turns 30, making life choices as she struggles with relationships and with herself.

“It felt ironic to call the film ‘The Worst Person in the World’ and have it be about love,” he continues. “Because everyone at some point in a relationship ends up feeling like [that]. But the title has another level, which is about self-acceptance. It’s an existential tale about personal growth — I like to joke that it’s my ‘Eat Pray Love.’”

The chapter structure allowed the filmmakers to take bigger swings between humor and pathos, covering years on end with one segment and spending the subsequent one over the course of a single, meaningful night.

“I like the idea that one life consists of many short stories,” said Trier. “The literary form made it possible to have all these moments and fragments from a longer period. [The main character] Julie is somehow awaiting her great destiny, waiting for fate to intervene; so putting that into a novelistic scale would mirror that sense of anticipation — and disappointment too.”

The film’s visual playfulness, however, stemmed from a very different set of concerns. “[Under the recent lockdowns,] cinemas were closed for so long, and I missed going; I missed the big emotions, the big colors,” the director said. “So we decided to shoot this on 35mm, and I told the DP, let’s make a visual feast. Let’s make this a big screen experience.”

As Trier and Vogt (whose own directorial effort, “The Innocents,” screens in Un Certain Regard) ready dual promotional tours, the longtime collaborators plan to regroup once their schedules calm later this year in order to set new plans in motion. Might they continue to build out their now three-strong series?

“Anders is getting older and Oslo continues to change, so who knows, maybe we will do a fourth [at some point],”  Trier said.

He then asked:  “What’s the word for a four film series — a quadrilogy?”