Ryan Gosling and Michelle Williams at the Cannes

Ryan Gosling and Michelle Williams play a married couple with issues in Blue Valentine.

But appearing at the Cannes Film Festival to promote the indie drama, the pair's offscreen chemistry was so undeniable that it's sparked intense speculationg among festivalgoers whether the two are an item in real life.

For now at least, Gosling and Williams are sticking to the we're-just-good-friends-with-a-movie-to-promote company line, even as they stole more than a few embarrassed glances at one another during a discussion of their film at the American Pavilion as the discussion turned toward dog poop and naked shower scenes.

"I had a hard time with it," said Williams. "I probably would go dead crazy telling [director] Derek [CianFrance] for six weeks why the script wouldn't work and why it couldn't play and I think my big dilemma was why, what's the event, what's the catalyst for this couple coming apart."

Gosling says he and Williams explored many of those issues in a pre-shoot rehearsal period, allowing them to at least pretend they were a real couple.

"Derek happen to set it up in a way so that we were living in a house for a month...and given a budget, including $200 for cigarettes. And I haven't smoked a cigarette since," said Gosling to laughter. He plays Dean, a chain-smoking furniture mover who falls for Williams' aspiring nurse, Cindy.

The actors, who have been pals since costarring in 2003's The United States of Leland, spent a month living together, getting all Method to make their characters convincing.

"For me, I discovered that it wasn't one event that caused me to hate this guy," said Williams of her alter ego's development.

While they may or may not be together in real life, Williams and Gosling have had no problem sharing embraces, getting all touchy-feely earlier this week at the Blue Valentine after-party on the roof deck of the Palais Stephanie Hotel.