Claudia Weill’s career as a director of feature films lasted just two years but she had an enormous impact. Girlfriends, her 1978 debut about two young female New Yorkers being pulled in different directions was a tiny independent film, but its influence has been rippling out ever since, detectable most notably in the work of Greta Gerwig and Lena Dunham.

“It’s only a joy,” says Weill, of seeing others pick up where she left off. “We all inspire each other.” Weill certainly thinks Frances Ha, which starred and was co-written by Greta Gerwig, took some inspiration from Girlfriends. “But it was a completely different film,” she adds, “and women’s friendships are a big subject.”

Girlfriends, which is being screened in selected cinemas this month, swirls around Jewish photographer Susan Weinblatt, whose relationship with her Waspy friend Anne Munroe is dented when the latter moves out of their apartment to start a family with her boyfriend. The screenplay, co-written with Vicki Polon, was based on Weill’s own experiences: she was eager to present a story with an imperfect, refreshingly relatable protagonist.

“I grew up in a family that expected me to get married and have children,” says Weill, who is now 74 and speaking to me from her home in Massachusetts. “I did that eventually, but it wasn’t the path I was on at all.” The film was Weill making peace with who she was while everybody around her was shacking up. Weill examines platonic and sexual relationships with breeziness, digging into themes with an honesty unfamiliar to many American cinemagoers. She was a documentarian before making Girlfriends and the naturalism carried over. “Making documentaries was film school for me,” she says. “I was learning to read behaviour. Girlfriends deals with miniature moments that reveal something about who the person is.”

She hustled Girlfriends into the Cannes film festival and then, off the back of that, cold-called some studios. After a bidding war, she sold it to Warner Brothers. Then Columbia Pictures came knocking, hiring Weill for 1980’s It’s My Turn, a romantic comedy starring Jill Clayburgh and Michael Douglas that scratched at similar territory and has its own charm. Weill did not enjoy the experience, though: being the female boss of an all-male crew meant being constantly undermined.

“I didn’t understand that an important part of being a director in Hollywood was political,” she says. “How you manoeuvre to get what you want.” Her biggest battles were with producer Ray Stark. “If you say to somebody like Ray Stark, ‘I’m not sure if so and so is right for the part’, he’d immediately see you as an antagonist. As a female, you could never make them – and ‘them’ is universally male – feel threatened. Especially as a young sexy woman. I was 30 and most of the men I was dealing with were middle-aged, or older. They’d never seen a woman direct. There was an instinct to put me in my place.”

At one point, she says, Stark ran his hand up her back on set, among the crew, and said: “Claudia, you’re not wearing a bra today.” She kept silent. “If I was to say, ‘Fuck you, get your hand off my back’ in front of an entire cast and crew, most of them middle-aged men, what would it have served me? I would have become ‘that bitch’.”

The experience did not endear her to the industry. “I certainly didn’t want to continue making films in Hollywood. I didn’t want to have to go through that again.” Instead she went into theatre and then television, directing the likes of Thirtysomething and My So-Called Life. “I didn’t really miss making a feature film,” she says.

In 2013, she directed an episode of Girls. Lena Dunham had met Weill at a 2011 screening of Girlfriends, which had bowled her over. “Lena said, ‘My mother’s been telling me for years I have to see this film! And I’m working on this TV series called Girls and I feel like I must have seen your film before because it’s all about that.’ And then she would give it to her cast and crew before a shoot, as reference. And that’s only flattering.”

At the end of Weill’s episode, there’s a phone conversation between Dunham’s Hannah and Allison Williams’ Marnie in which both are unhappy but pretending otherwise. It’s very reminiscent of Weill’s debut. “That scene does reflect stuff in Girlfriend,” she says. “When you feel like you can’t be honest with your girlfriend, then you’re really alone. You’re really alone. And that’s sad.”

Such themes are evergreen, which partly explains why Girlfriends still feels contemporary. Dunham has praised the film for “the complex relationships, the subtlety, the odd comedy that was awkward long before awkward was cool.” And of late it has enjoyed a resurgence. In 2019 it was entered into the American Library Of Congress for being “culturally, historically, or aesthetically significant”, and last year Criterion brought it into their collection.

“It’s amazing to have a film live over 40 years and still be fresh. Last night Quentin Tarantino screened it at his cinema in Los Angeles, a double-bill of Girlfriends and It’s My Turn, and it was way sold out. It’s very gratifying that this little film you made so long ago is still speaking to people. It’s very moving.”

Weill now teaches film directing and has no plans to make another herself. “I’m kind of over it,” she says. “I really love teaching. But you know, there’s always those films, those stories you haven’t told. Who knows what I’ll do with that?”

• Girlfriends is in selected cinemas from 23 July.