Charlyne Yi, left, and Michael Cera in a scene from Paper Heart, where they play fellow comedians whose relationship is messed up by ever-present cameras. (Sundance Institute/Associated Press)

Charlyne Yi swears that she and Brampton, Ont.-raised Juno star Michael Cera are not and have never been romantically involved.

In her film Paper Heart, Yi and Cera are an on-screen couple whose relationship is marred by the camera. But off-screen, she says they're just friends, and they laugh about the media reports romantically linking them.

"I don't want to freak anyone out, but no, it's just film," the 23-year-old sometime comedian and filmmaker told CBC's Q cultural affairs show on Friday. "Just because you're a girl and guy doesn't mean you're instantly attracted to each other."

In person, Yi laughs frequently and displays none of the polish or pretence of an actress. Is the denial about Cera just a way of hiding a broken heart?

Charlyne Yi explores the mysteries of love in Paper Heart. (Alliance Films)

"We're not dating. No. I swear ... Never," she said.

Paper Heart, which earned Yi a screenwriting award at Sundance, features Yi, playing herself, travelling from Los Angeles to New York seeking out examples of true love.

The film is "half documentary and half a film" said Yi, who composed and performed the soundtrack along with Cera and is also executive producer and puppet designer for the indie film.

Yi said she set out to make a documentary, but along the way, she came across so many interesting stories — like the couple who met at 14, married at 16 and are still in love decades later — that she wanted to find a way to tell them.

In Paper Heart, the character called Charlyne Yi, played by Yi, is a woman who doesn't believe that love is anything but a fantasy.

Yi admits she's scared of the world of relationships, especially after speaking with friends in their 40s and 50s who are single.

"You wonder how many relationships have they been through, and they end up alone? Am I going to end up like that?'" said Yi.

On film, Yi brings a great deal of cynicism to the topic of love. In real life, she just has lots of doubt.

"Not so much cynical but just questioning," she said. "Will [you] find a stranger where you're compatible and want to spend the rest of your life together and is that possible? You see so many divorces now, I think you really have to fight for that relationship to work out."

Yi co-wrote the screenplay with Nicholas Jasenovec, the director of Paper Heart, but much of it was improvised because what they wrote didn't always work out. Some of it is just candid interviews with ordinary people.

"It's really terrifying," Yi said of the filmmaking experience. "People were entrusting us with this money, and we set out to make this film — we've never made a documentary, we've never made a film, I don't know how to act, I don't know how to talk to people, so we were learning all these things as we went."

Yi has braved the tough world of standup, earning the support of comedian Bill Hader and had a role as the giddy roommate in Knocked Up. She also has worked with puppets, plays in a band and does visual art.

Paper Heart showed her she loved filmmaking, but she has as many doubts about that as she does about relationships.

"I'd always wanted to make films," she said. "I wanted to be a director when I was in high school… Now I'm not so sure. It's a lot of work. It's terrifying to have all this responsibility for a film."

Paper Heart will be in commercial release Aug. 7.