Though Nev has never met Megan, he falls for her after numerous phone and Facebook messages, but when he decides the time is right to meet her, things take a strange turn.

Speaking to Reuters Television, Schulman said the film is best viewed with little knowledge of the story.

"Yeah we'd like people to know as little as possible or nothing. If your trailer could just say go see "Catfish", trust us you'll like it, that's what it would be. Because the less you know the more authentic your experience will be to my experience which was intense and emotional and fun and shocking and suspenseful and scary. I mean those are all the things I felt, living it that I hope you feel watching it. "

Schulman said he went into the documentary with high hopes of a happy ending with Megan.

"I wanted it to be the love of my life. I wanted it to be my next girlfriend and maybe a geographic change in where I was living, to the country. I was looking for love. This wasn't a movie, for me."

Several media outlets have questioned the film's authenticity, saying various aspects of the story's twists and turns did not seem believable.

Schulman says accusations of the film being fake have been puzzling.

"It was just strange to have people question something that happened in my life that I was there for, that was a very emotional and difficult experience for me to go through. I've come to terms with it. I understand why people could think it's somehow manipulated or staged, or false. I can't imagine how there's any justification for it. I don't really see the evidence, I don't understand the argument but I do appreciate that in a time when the line between fiction and non-fiction becomes increasingly blurred, people are on guard."

The film was a big hit at Sundance earlier this year and has had excellent reviews, even from critics who claim it's fiction.

"Catfish" is out in UK cinemas now.