Michelle Williams and Ryan Gosling are rumoured to be dating, after putting on a surprising display of public affection at the Cannes Film Festival.
The pair play a married couple in Blue Valentine and sources on set say their steamy physical relationship has crossed over into real life.
At Tuesday's photocall at the Cannes Film Festival, the two held hands constantly and shared little private jokes.
On the red carpet they remained hand-in-hand. Later at an afterparty, Gosling spent most of the night with his arm around Williams.
"You know actors who meet on movie sets. It can be the most romantic place in the world," a set worker said.
If the two are dating, it is no wonder. They spent eight hours filming a naked shower sex scene for Blue Valentine.
Gosling said it was "intense": "Leading up to it was like doomsday. We knew we were going to have to get totally naked in front of each other and we’d both been putting on weight (deliberately, for the aging of their characters), and it wasn’t going to go well," he said.
"Just tons of rejection and it was going to be awful. And I didn’t expect the hotel soap to be so ..harsh! But we were just there all day and started getting rashes."
The couple have both had high profile relationships before, with Gosling best known for dating The Notebook co-star Rachel McAdams and Williams for having a child with the late Heath Ledger.