EVEN if the idea of a romantic movie usually leaves you feeling cold, if not a little nauseous, don't dismiss Before Midnight.

It's about as far from a cliched romance as you can get.

As one of its stars, Ethan Hawke, put it: "Most romances seem to have either a female agenda, where the guys are all dopes, or a masculine idea of what romantic love is supposed to look like, with Eva Mendes crawling across the floor in a bikini.

"What's so wonderful about this movie is it's kind of 'genderless'. It's fun to make a romantic movie that I'm not ashamed to ask my male friends to go see," laughs the 90s heart-throb, who, at 42, still boasts a boyish quality.

His co-star Julie Delpy agrees. "It was our goal when we did this, that it's neither macho or feminist or man-hating," says the 43-year-old French actress, looking chic in a black dress.

While it can be watched as a standalone movie, Before Midnight's actually the third in a series of films about Jesse and Celine, two characters who met in 1995's Before Sunrise. In that movie, the two 20-somethings began chatting on a train, and impulsively disembarked to spend a day and night exploring Vienna together.

It ended with the expectation they'd meet up six months later, but as the 2004 sequel revealed, that rendezvous never materialised.

In Before Sunset, Celine unexpectedly showed up at a Paris bookstore when Jesse was promoting his novel inspired by their night in Vienn a. Though both in relationships, they walked the streets of Paris rediscovering each other, realising their bond was as enthralling as ever.

Now it's nine years on, and Jesse, a successful author, and Celine, an environmentalist, are facing all the complexities of maintaining a long-term relationship together.

"Often in married life, it's either some kind of cornball, whitewash thing where everybody's OK, or it's heavy drama – alcohol, stress, they secretly hate each other," notes Hawke, a Texan native, who has four children – two from his first marriage to Uma Thurman and two with his present wife and his children's former nanny, Ryan.

Before Midnight opens with the Paris-based pair enjoying the summer at a writers' retreat in Greece with their twin daughters. But while the landscape may be serene, the state of their relationship is far from it, and we soon realise geography's weighing heavily on Jesse's mind.

As Hawke continues: "It's telling that the movie starts with the unseen casualty of the last movie – a child who has grown up separated from his father," he says, referring to the son from Jesse's previous relationship, who he waves off at the airport following his stay with the couple.

"Their relationship started with a choice that Jesse made – to follow his heart," says Delpy, who has a child with the composer Marc Streitenfeld. "But that comes with consequences, and now we find them in a situation where they have to make another choice."

Should they go to America to be near Jesse's son? Should Celine accept a job that would keep them in France? Do they still love each other and want to be together?

These are the questions they ask themselves during a night at a luxurious hotel, gifted to them by friends, where, despite the idyllic setting, realities intrude.

"There's no bad guy in this but they still have to make compromises and they're asking who's making the most and what compromises might jeopardise their relationship, and their love," explains Delpy.

Hawke agrees: "Here are two well-meaning people who actually love each other and want the best for each other, but it's still hard.

"For anyone in a long-term relationship, it's whether your lives are still growing on the same road or does one need to change the road to keep growing?"

The night builds to a fight; one in which nasty and hurtful things are said, but while it makes uncomfortable viewing, Delpy doesn't see the turn of events as necessarily negative.

"When I see people that are too perfect together, there's something really weird," she says. "When I see people arguing and having issues, I'm like, 'Yeah, this is a real couple, I believe it'."

Besides, she wanted Celine – who she describes as "not good, not bad" – to be a fighter.

"So many people in relationships give up. That's what destroys them, when the woman or man goes, 'Fine, let's do it like that' and then they're never happy. They build up so much more resentment than if they were fighting it in the moment."

Before Sunset, which played out in real time, earned a best adapted screenplay Oscar nomination for Hawke, Delpy and the director Richard Linklater. The trio also co-wrote this movie and, as ever, strove to depict scenes as naturally and authentically as possible.

This involved many long, uncut scenes filmed in one take.

"The style breaks the language of typical film-making and, in a way, you feel you're witnessing something very real," says Delpy, who has written and directed movies such as 2 Days In Paris and 2 Days In New York.

l Before Midnight is now screening at Glasgow Film Theatre.

JULIE DELPY, who has starred with Ethan Hawke, above, in Before Sunrise, Before Sunset and Before Midnight