The 2004 book offered women a shocking revelation: If a man doesn't jump at your end-of-date invitation to come in for "coffee" he's probably not interested.

It was an immense bestseller that got translated into a bunch of languages and changed women's lives forever -- groundbreaking stuff. "You mean," we said "that if he doesn't call he's not interested?" And we were floored. Because women will tell ourselves anything and make up any excuse (He's commitment-phobic because his mother smothered him. He's really busy at work. He must have lost my number...) to avoid admitting that maybe we just don't really turn his crank.

And now, four years later, He's Just Not That into You is being released as a feature film starring Scarlett Johansson, Jennifer Aniston, Drew Barrymore and Ben Affleck. The official website says the film "tells the stories of a group of interconnected, Baltimore-based twenty- and thirtysomethings as they navigate their various relationships from the shallow end of the dating pool, through the deep, murky waters of married life, trying to read the signs of the opposite sex...and hoping to be the exceptions to the 'no exceptions' rule."

Should be fun. Will they ever learn? We haven't. All those millions of books sold and we still don't get it. Not really. Partly because we don't want to.

Being single is confusing, particularly in this day and age when we are constantly bombarded with mixed messages from our peers and pop culture. One voice whispers that we don't need to be part of a couple to be happy while the other warns that we're going to die alone. Our friends praise us for being independent individuals with one breath and bully us into blind dates with the next.

And then there's the endlessly annoying question: Why are you single? Tuccillo aims to subvert this question in her latest book, a novel, How to Be Single.

In it, plucky protagonist, 38-year-old Julie Jensen says, "A human being's desire to mate, to pair up, to be part of a couple, will never change. But the way we go about it, how badly we need it, what we are willing to sacrifice for it, most definitely is changing.

"So, maybe the question isn't anymore 'Why are you single?' Maybe the question you should be asking yourself is 'How are you single?' It's a big new world out there and the rules keep changing."

And so we explore the lives of Julie's friends -- Serena, a modern day ascetic; Georgia, who got dumped by her husband for a "whore/samba teacher"; Alice, who quit her job as an attorney to date full time; and Ruby, who substitutes relationships with cats for human ones -- and how they are single. And we follow Julie on a trip around the world as she explores how women are single in different places.

It's a trip Tuccillo actually took in real life, travelling to countries that included France, India, Italy, China, Iceland and Australia and talking to both men and women about the experience of being single.

Here she discusses some of her thoughts and discoveries:

Lavalife: So, you became an expert on being single through working at Sex and the City.

Liz Tuccillo: Isn't it awful? People are always saying, as an expert on dating we would like you to tell men what they should get their girlfriends for Valentine's Day. And I'm like, really? Because I'm actually not an expert on dating. On being single I guess you'd call me an expert.

LL: So, how much of this book is autobiographical and how much is fictional?

LT: None of the stories, none of the shenanigans, are true at all. But what the women said and their points of view are all true.

LL: So, it's representative of a true story.

LT: Yeah.

LL: What inspired you to take off and travel the world talking to single women?

LT: Countries all over the world had bought the rights to He's Just Not That into You and France still hadn't. And it was so irritating to me. It became like the guy who doesn't like you so you like him more. I became obsessed with why France didn't want my book. And then I became interested in what it is that goes on in France that they don't think the book applies to them. I realized they don't have a single culture there. They don't have Bridget Jones' Diary books or films. They have films about love and marriage and infidelity but not about the single girl. I started wondering why that was. So, in a nutshell, France didn't want to buy my book. It really annoyed me. I wanted to find out why and that started this curiosity about how women are being single in different parts of the world.

LL: So, why do you think France doesn't have a culture around being single?

LT: When I went there, there was just a complete, innate sense of self-esteem and entitlement among the women. Their mothers already told them they're great as they are, that they should never chase a man and that they always need to have pride. They said 'Why would I need a book to tell me a guy's not into me if he hasn't called me?' They thought it was the funniest thing. 'So, you made a lot of money writing a book that tells women that when I guy doesn't call her he's not into her?'