Mary, the central character of Aleem Khan’s debut film After Love, is a white English woman who met her Pakistani husband as a teenager on the London housing estate where they both lived. After they got married, they moved to the Kent coast. Mary converted to Islam, started to wear traditional dress, learned how to cook curries from scratch and to speak Punjabi.

It does not take an enormous amount of detective work to understand from where Khan drew inspiration: his mother is a white English woman who met her Pakistani husband as a teenager on the London housing estate where they both lived. After they got married, they moved to the Kent coast; she converted to Islam, started to wear traditional dress, learnt how to cook curries from scratch and to speak Punjabi.

So far, so precisely a recreation of Khan’s own parents’ lives. Khan raided their wardrobe for costumes and their house for Islamic art to use as set dressing. But the plot proper of After Love is not autobiographical. After her husband’s death, the fictional Mary discovers he has a secret girlfriend and child in Calais. Mary befriends and enters the employment of the other woman, who does not realise her new cleaner is her lover’s widow. “I took my real mum and put her in a fictional scenario and in jeopardy. I found that really interesting,” says Khan.

We are speaking in a cafe near his home in London. Khan, who was nominated for a Bafta in 2015 for his short film Three Brothers, is neatly groomed and dressed in black, and there is a deliberative self-assuredness when he speaks. He says he arranged for his mother to meet Joanna Scanlan, the actor who plays Mary, so she could teach her how to make saag paneer. His mother also brought bags of clothes round so they could go out together. “It was really important that Joanna understood the importance of this character to me and the importance to the story. Joanna could live in the costume, go out in the world, wear the headscarf and see how people treat you differently – because they do.”

We frequently see Mary pray in the film, and Khan says it was crucial for him to show a practising Muslim “who was comfortable with that part of their identity”. “We rarely get to see the full inner spectrum of a Muslim character at the centre of a story,” he says. Without that, “we can’t have the progress or visibility we deserve or need”.

Yet After Love is ultimately less about faith than grief, loss, love and identity. “It’s a deeply political film for me, but the politics in the film are quite quiet,” says Khan. “It feels like my whole life is in this film, even though the story isn’t a biography of my own life.”

Khan says his childhood and adolescence were dominated by confusion over his identity: “I grew up within two cultures, and the feeling that I never fully belonged anywhere operated at quite a cellular level within me.” Khan was also struggling with his sexuality. “I always knew that I was gay,” he says, “but it was buried deeply because I carried a huge amount of shame because of it. I just wanted to fit in and I was in denial.”

At university he borrowed a VHS of My Beautiful Laundrette. “I was terrified because I thought the librarian would then know I was gay. I was so afraid of anyone knowing. I remember taking it to my room and literally watching it with a blanket over the TV. I’d not seen anything like it. It was about seeing something I connected with for the first time. That was a very powerful experience.”

For Khan, the turning point came at university, when he began to come to terms with his own sexuality – and to lose faith in his religion. “I was grappling with how to reconcile between gay and Muslim,” he recalls, “and it was only later that I understood that identities are not independent or uni-dimensional, but multiple and intersecting.” His crisis coincided with something similar that was happening to his mother. “Things happen in families when the kids grow up,” is all he will say about that.

“There was something about this emotional crossover that had always stayed with me,” he adds. “The question of what is left of yourself when you change yourself and revolve so much around someone else. When that person leaves or dies, how do we begin to recalibrate and find our sense of self again?”

Khan consciously explored such issues while working on the script; one of them being the painful story of the death of his six-month-old sister, Shereena, when he was four. He grew up keeping his sister’s teddy in the bottom drawer of his desk. “I don’t really remember anything about her,” he says, “but growing up there was always a sense that someone was missing.”

Khan says he digitised old home movies from VHS tapes and had a wall of photos of his family through the years tacked to the wall by his writing desk, a few of which had Shereena present. “I’ve always thought that I remembered the day that those photos were taken, but I can’t be sure if it was just my subconscious trying to create attachments through the physical pieces we had left of her. It felt like I’d lost a sister and it hadn’t affected me – but it had. Making this film allowed that dormant trauma to find an outlet and purpose.”

After Love features a scene in which Mary visits the grave of her husband – and the child she lost years before. Yet the sense is that despite such tragedy, and the betrayal of her husband’s double life, she will persevere. For all the pain that death and betrayal may have inflicted, life will go on. “The deceit is huge, but it doesn’t negate or remove the love. The world does not go down in flames. Life is far messier. You carry on and you recalibrate so you can live with it.”

• After Love is released on 4 June.

• This article was amended on 26 April 2024 to remove some personal details.