So, what is it about Chris Waitt that makes him so repugnant to the opposite sex? That's exactly what the film-maker sought to find out when he decided to track down all of his old flames and ask them what went wrong. The end result, a documentary titled A Complete History of My Sexual Failures, makes for eye-watering viewing as the hapless and bumbling Waitt, utterly baffled as to why he has been serially dumped by every single girlfriend from the age of 11, embarks on a journey of cringe-inducing self-discovery.

Unfortunately for Waitt - think a goofier version of Michael Moore or Morgan Spurlock - the list is as long as it is painful. His childhood sweetheart, Dawn, says she ended their relationship after "you got drunk at a wedding, pinned my mother up against the wall and kissed her", while his most recent ex, Alice, tells him to "f*** off" through the letterbox when he shows up at her house unannounced.

Former girlfriend Danielle, meanwhile, reveals Waitt is the last white man she dated. "I've managed to put her off a whole race of men," he says, peering woefully into the camera. Another erstwhile love, Za, a psychiatric nurse, reminds Waitt that, while they were dating, he suffered delusions that he was Jesus. "You say every woman you've been out with was crazy but I think you drove them to that point," she says. Ouch.

While it makes for comic viewing, the film does throw up a major question - what kind of person would willingly lay bare their life like this? I figure either someone who's a complete egomaniac or utterly naive. As it turns out, Chris Waitt is a bit of both. He wanders into the bar of an Edinburgh hotel wearing a hooded top, jeans and grubby-looking plimsoles that have seen better days, his mop of blond hair veering towards the messy side of tousled. In tow is his Moscow-born girlfriend of one year, Alex Boyarskaya, whom he met while making the film.

He is still cringing at the memory of the Q&A session which followed the UK premiere of his film the previous evening (many of his ex-girlfriends were in attendance). "There were some very pointed personal questions from people who knew things about me from outside of the film, but I'm glad to say I survived it," he says, shuddering.

Had he considered beforehand how the film would impact upon the lives of the women involved? He looks suddenly sheepish. "I'm afraid I don't think I did," he says. "I'm glad to say, though, all the girls in the film appear with consent. For the most part I think they're reasonably happy about it. Some would rather not have too much publicity, others don't really mind."

He admits he completely underestimated the can of worms he would open. "The main thing was to try and find out what was so bad about me as a boyfriend," he says. "That seemed to be quite a big question for me. I've been dumped so many times I felt I really needed to get to the bottom of that." But he didn't expect to be confronted with such a vast catalogue of flaws. His former girlfriends call him emotionally backward, unreliable, insensitive and unstable, among other things.

"I didn't massively think it through," he says. "The most I expected was that it would be a bit like a school project, where I could find out a few things that were wrong with me and, if they were easy enough to address, I could apply that to a new relationship. I didn't think it would get into such personal and intimately complex areas. In retrospect I'm glad it did, because it makes for a much more entertaining, rollercoaster ride of an experience. It also became much more cathartic than I originally imagined. I thought it would be much more journalistic but it's hard to maintain objectivity when you are the subject. That's why it probably went off the rails a bit."

Born in Worthing, West Sussex, and now based in London, Waitt, 34, spent much of his twenties living north of the border - hence the legion of Scottish exes who appear in the film. The intimacy which came from re-visiting the realms of his past relationships appears to have caught him off guard. There were times, he says, that delving to the root of his romantic inadequacies left him thoroughly depressed. One of the most common grumbles among his ex-girlfriends was his poor technique in the bedroom, and this led to some navel-gazing of the most excruciating kind. Midway through the film, proceedings go off on a bizarre tangent as he becomes increasingly preoccupied with his lack of sexual prowess - and, it transpires, major impotence problems.

After visiting a GP, a sex therapist and - most jarringly - a dominatrix called Mistress Maisie in an S&M dungeon (yes, you see everything), Waitt takes three times the recommended dose of Viagra and runs amok in the streets of London, asking women if they will sleep with him. The sole upside of this scattergun mission is that Waitt is now dating Alex, a 26-year-old Russian journalist he bumped into that day (she offered him only a hug).

With hindsight, Waitt acknowledges a degree of regret at his frankness. "Sadly, if I end up as a poster boy for anything it will be for impotence - which is really a terrible thing to be known for," he says. "After screenings I get lonely, weird guys come up and tell me about their sexual problems. That's certainly not what I hoped for. Probably a small part of me thought some lonely girl would watch the film and say, He's the guy for me, he's perfect.' As it happens I don't need a girlfriend now, but I haven't had that many girls come up to me. It's only been lonely guys, and middle-aged women who want to mother me."

Another downside is that many people feel they now have an access-all-areas pass to his private life. "A classic question we're asked at film screening Q&As is: How's your sex life?'" Waitt gestures towards his girlfriend, who is perched next to him on the sofa. "She normally answers that question. Go on, say what you usually say," he coaxes her.

"Chris made this film, it was before we met, it wasn't my choice," she says. "So if someone asks that question, we're not going to answer." Waitt turns the tape recorder back round to him. "But it's better," he insists. "My sex life is better than it was. I can tell you that." Beside him, Boyarskaya rolls her eyes in good-natured exasperation.

Another label Waitt has been given is "the male Bridget Jones". What does he make of that? "I don't think I'm quite as pretty as Bridget Jones," he says. "She was quite sweet. Or at least Renee Zellweger who played the character in the film was."

Boyarskaya appears incredulous. "What?" says Waitt. "Renee Zellweger is she's a Hollywood star!" His girlfriend looks mutinous. "She isn't, she's not pretty at all," she counters, shaking her head. "OK," says Waitt, laughing. "That's your opinion."

For all his emotional faux pas, there's an endearing likeability to Waitt. In person he's disarmingly charming. "I think the editor persuaded me to remove some of my more witty, funny and amusing one-liners," he deadpans. "Also, the girlfriends themselves were allowed to have an influence on the edit, so they didn't generally like it in scenes when I was being quite funny. The person on screen is a lot less funny and intelligent than I am in real life."

I'm curious as to what's the biggest lesson he's learned from the experience. "Let sleeping dogs lie," he says - then blanches as he realises what he's said. "Um, no, maybe not dogs. Change that to girlfriends. Let sleeping girlfriends lie."

A Complete History of My Sexual Failures is at the Cameo, Edinburgh, from tomorrow and will be showing at cinemas around Scotland during July.