Given the emotional cliff-hanger where left its audiences, that's almost cruel. The film ends as Jesse deliberates in Céline's apartment: should he stay or should he return to his wife and child? "I felt very sure at the end of the second film that Jesse does not go home," says Hawke. "Not right away anyway. I really enjoyed that practical sense of how damaging that would've been, the way he ended that marriage. A lot of the pain of divorce is not actually over the fact of the divorce, but how people obsess about how it happened."

Thankfully, Hawke - who was going through his own split from actress-wife Uma Thurman at the time of - decided to reunite with Linklater and Delpy to bring back Jesse and Céline. Continuing this beguiling US indie romance, ("we ran through quite a few titles," says Linklater) immediately shows that Jesse didn't get on that plane back in Paris. He stayed with Céline and - nine years on - they now have twin daughters of their own.

And this time, there's not the innocence of the first encounter of , nor the sexual frisson of . "Flirting in this one would've been a cheat," Delpy says. "It would've been basically f***ing with the audience; it's retarded."

Rather this latest outing looks at the realities of romance, the pragmatic day-to-day nature of how to keep a marriage alive. "We're going to deal with their real life," says Linklater. "We see them interacting with people - children, friends, each other. So it's more grounded in the real world."

Set in Greece, the film begins at the end of summer, as Jesse says "goodbye" to Hank (Seamus Davey-Fitzpatrick), his now-teenage son from his first - and failed - marriage. They have just spent the holidays together on a writers' retreat in the southern Peloponnese. As 42-year-old father-of-two Hawke puts it, "Anybody who's divorced will tell you that the transition at the end of the summer is very painful. You get confronted with the facts of your divorce."

While an emotional Jesse is left torn, desperate to move his family to Chicago so he can be near Hank, Céline has been offered a "dream job" in Paris. "It's really about compromise," says Linklater. "So much of life is."

The way he sees it, deals with the issue of spontaneity. "If you're going to be a consistent friend, spouse or parent, it takes away the spontaneity," he says. "It's easier to feel that way as you get older, but the challenge is to meet your obligations and still feel like you're an alive, spontaneous person who can still maximise whatever you're most interested in."

As far as its French lead actress is concerned, is far removed from the Hollywood romances that dominate cinemas. "Sometimes I see American romantic comedies and there are people in their 40s who have problems with people in their 20s! They have issues! The reality of Americans is not that. Hollywood - the dream machine - feeds people. I think we get the chance to explore a little further, without pretention or anything," Delpy says, "to try to be a little true. Just a little bit of truth is nice."

Much of this "truth" comes from just how close Hawke and Delpy - who, as with , co-scripted the film with Linklater - are to Jesse and Céline. "In some strange way, these characters are alter egos of Julie and I," says Hawke. What does his director think? "Jesse and Céline are constructs; they're not them," says Linklater. "But there's something about them that runs parallel - to all of us. I'm in both of them. I feel equally in Jesse and Céline. And I think they would start to say that about each other too. I don't think Julie would say she's Céline. They write so much stuff for the other character, and we all participate in that."

When they started , Hawke and Delpy's first stage in their "writing assignment" was to sit down and watch the first two films back-to-back before throwing ideas around. That they've worked together for so long made this considerably easier, says Delpy. "We're not polite with each other. When I think it is an obnoxious thing that Ethan's written, I'm going to tell him right away. Ego doesn't get in the way as much when you know each other well."

What impresses most about is that while it appears to be semi-improvisational, it's actually highly scripted. "We never improvised one word," says Delpy. "Rick's very meticulous about how he wants to shoot things. You can't do a 13-minute shot, and tell a story, and improvise at the same time." She's referring to the scene where Jesse and Céline return from the airport in their car, conversing in an unbroken one-take scene.

Still, the script was finalised only when everyone arrived in Greece, and began to soak up the atmosphere. It was Linklater who suggested using the beautiful Mediterranean country as the setting. "I like the ancient-ness. I think we were all attuned to that," he says. "It really is profound when you are there … we never reference it, obviously. But whatever goes on between people, you realise has been going on forever - and it [always] will."

The question is, would they consider a fourth outing? "I tell you, I feel like I left Greece two months ago," sighs Delpy. "I feel like I could be doing a take tomorrow with Ethan! So we can't even think of a fourth film right now. Those films are so intense in the work, it takes us nine years to recover!"

Still, how fascinating would it be to see Jesse and Céline hit their 50s? "I want to do St Petersburg next," Hawke says, grinning. Now that would make a great backdrop to their midlife malaise.

Before Midnight