Céline Sciamma’s Portrait of a Lady on Fire should carry a health warning: “This film may cause uncontrollable swooning.” Everywhere the French director’s period lesbian romance has been screened – 40 film festivals in total, from Cannes to Aspen and Zurich – it has produced a dizzied, infatuated reaction of the sort not usually associated with a subtitled drama about enlightenment- era portrait artists. All over the globe, Sciamma has seen the passion her film generates, “a tension with the audience – there’s electricity. That’s the thing when you make a love story. You get a lot of love.”

Well, with one exception. “In France, they don’t find the film hot,” says Sciamma matter-of-factly. “‘[They think] it lacks flesh, it’s not erotic. It seems like there are some things that they can’t receive.”

It’s a point of view that many who have seen Sciamma’s simmering tale, about the love affair between an 18th century noblewoman and the woman hired to paint her, would hotly dispute. Yet, she says, the critics back home haven’t taken to her film at all, a tepid reaction by which she seems unsurprised.

“It’s a very bourgeois industry. There’s resistance to radicalism, and also less youth in charge. ‘A film can be feminist?’ They don’t know this concept. They don’t read the book. They don’t even know about the fact that ‘male gaze’ exists. You can tell it’s a country where there’s a lot of sexism, and a strong culture of patriarchy.”

Adèle Haenel, left, and Noémie Merlant in Portrait of a Lady on Fire. Photograph: AP

Throughout her career, Sciamma has sought to kick against this prevailing culture with a style of film-making that puts women front and centre. She is a founding member of 50/50x2020, the Time’s Up-style movement seeking to redress the gender balance in international film-making, and is wearing a 50/50 badge when we first meet in the wake of her premiere in Cannes. In person, she speaks in confident, thoughtful English, though with the odd, sweary flourish. (“I don’t give a fuck. I don’t give a shit about it,” she says when the subject of the controversial lesbian film Blue Is the Warmest Colour comes up.)

Born in the Parisian suburbs, Sciamma wrote the script for her first film, Water Lilies, while she was still at school. The film, a tense, at times troubling drama about three teenage synchronised swimmers, was screened at Cannes and followed up with Tomboy, which tracked the adolescence of a gender-nonconforming child. Most recently, there was the acclaimed Girlhood, which documented the rollicking lives of a group of French-African schoolgirls. The focus of Sciamma’s output is squarely on women, usually young women on the cusp of some major change – and how they look at themselves and each other.

It is this art of seeing that is central to her latest – and best – film. Portrait of a Lady on Fire traces the crackling relationship between Héloïse (Adèle Haenel), a young woman living on a remote island near Brittany, and Marianne (Noémie Merlant), the artist tasked with painting a portrait of her, which will be sent off to a prospective husband for evaluation. (A process people have likened to an enlightenment-era precursor to a Tinder pic, Sciamma says, smiling.)

The trouble is, Héloïse has shown little willingness to be married off, and has refused to sit for other portraits, so Marianne must capture her likeness surreptitiously while pretending to be her walking partner. Soon Marianne’s searching looks towards her subject are returned in kind. The result is a film in which every covert glance feels weighted with meaning, both a commentary on and celebration of the power of the female gaze.

With its lush visuals and rippling period detail, Portrait of a Lady on Fire might seem a jolting departure for anyone familiar with Sciamma’s earlier work. Where her previous trio of films felt fizzingly contemporary, Portrait is often serenely still: the closest it gets to the raucous rendition of Rihanna’s Diamonds in Sciamma’s 2014 film Girlhood is when Marianne blasts out Summer from Vivaldi’s Four Seasons on the harpsichord. Yet beneath the period trappings there is something strikingly modern about the film’s outlook. It shows little interest in the cliches of doomed romance that similar LGBT love stories would usually lean into. The inevitable melodramatic moment where the lovers get caught thankfully never materialises. Instead, Sciamma decided “to concentrate on the potential and fulfilment of their love story”, even though history tells us it can’t succeed.

Girlhood (2014). Photograph: Hold Up/Lilies/Cnc/Arte France Cinema/Canal+/Strand Releasing/Kobal/Rex/Shutterstock

Modern, too, is the depiction of enlightenment-era art, a period that, it might be assumed, was overwhelmingly male-focused, but that Sciamma’s research showed to be quite the opposite. “I was ignorant of the fact that it was such an important time for women painters. We didn’t get the memo, because it had been erased from the history of art.” In fact, the female painters she unearthed were so “vivid and numerous”, she felt that to make a biopic of one would undervalue the rest. “So I decided to invent one to talk about all of them.”

This reclamation of women’s art extends not just to those doing the painting. “We call models ‘muses’, and that’s mostly what’s left in the history of art for women artists,” Sciamma explains. “Dora Maar was the muse of Picasso but also a photographer at the centre of the surrealist scene. And Gabrièle Picabia was the wife of [avant-garde painter Francis] Picabia but also the brain of his work. It’s about co-creation, not this fetishised, silent woman standing there beautiful and mute.”

So, in the film, the portrait becomes a collaborative act between artist and subject, Héloïse’s thoughts and gestures shaping and informing the finished work. In this, art imitates life: the film’s central relationship evokes that of Sciamma and her lead actor Haenel. The pair first worked together on Water Lilies and were, until recently, in a relationship.

“We met through cinema and had our dialogue on set,” Sciamma says. “It’s an intellectual relationship that never stopped, even though we didn’t officially work together for 12 years. We’ve been growing and thinking together. And I wanted to portray that.

“I wanted it to be open,” she continues. “I wanted it to be generous and full of ideas, ideas about cinema. But it mostly tells about the present of our relationship, how we had this dialogue on this particular film and how we keep writing our relationship today.”

Haenel made headlines in November after alleging that she had been sexually harassed by the French director Christophe Ruggia when she was 12. Ruggia, who denies any wrongdoing, was charged with assault of a minor in January. In a country where the #MeToo movement, and its French equivalent #BalanceTonPorc, haven’t always been enthusiastically received, Haenel’s decision to speak out was fraught with risk, yet she has received praise for her bravery.

When I catch up with Sciamma in London in the new year, she is reluctant to speak about Haenel’s allegations, but is heartened by the response to them. “She had support, people believed her, so that’s new.” Still, resistance to #MeToo remains an issue, as seen last month when An Officer and a Spy, the new film by disgraced director Roman Polanski, received the most nominations at France’s answer to the Oscars, the Césars. The decision prompted 400 members of the French film industry to demand “profound reform” at the César academy, and saw the resignation of its entire board. Speaking after the nominations were announced, but before the board’s mass resignation, Sciamma simply said: “It’s France.”

Portrait of a Lady on Fire received 10 nominations at the Césars, to add to a swelling number of festival and critics’ choice prizes the film has won in the past eight months. One accolade notably absent was an Oscar nomination: with only one film from each nation able to be submitted for the Academy’s best international film award, France elected to submit another film, Ladj Ly’s state-of-the-nation cop drama Les Misérables, for the prize. It was a decision that prompted howls of protest from admirers of Sciamma’s film, but the director is relaxed about the situation. She has seen the glad-handing Ly has been forced to do during awards season and, “It’s eating up his life!”

Sciamma has enjoyed some reflected Oscars glory, though. Portrait of a Lady shares the same US distributor, Neon, as Parasite and throughout awards season she has been cheering the film on. After Parasite won the top prize at the Screen Actors Guild awards, Sciamma says that she got in touch with the director Bong Joon-Ho. “I texted: ‘I feel like I won, too’ because we’re on the same team,” she says. On Oscar night a joyous video of Bong and Sciamma celebrating together went viral. She says happily: “I have nothing to do with [Parasite’s awards season wins], but it’s a win for an idea of cinema we share.”

Portrait of a Lady on Fire is out on 28 February