In The Breaker Upperers, two best friends run a small business doing the dirty work of emotional cowards: ending relationships. Or as one broken-hearted woman yells: “You work for weak arseholes who don’t have the guts to talk to their partners!”

It’s the kind of avoidant, misanthropic premise that could have become a particularly problematic episode of Seinfeld. But in the hands of actors, film-makers and feminists Jackie van Beek and Madeleine Sami, it becomes something else: a bright, bouncy debut, filled with the playfulness, heart and loveable guilelessness that we have come to recognise in New Zealand comedies.

It’s also a neat fit for executive producer Taika Waititi, the Kiwi who’s burst from indie maverick (2014’s What We Do in the Shadows, 2016’s Hunt for the Wilderpeople) to million-dollar franchise man (last year’s careening Marvel joy, Thor: Ragnarok) without compromising his fantastical, childlike, imaginative storytelling.

The Breaker Upperers takes that same imaginative blueprint and stretches it into a buddy comedy and skit-show hybrid. For Jen (Van Beek) and Mel (Sami), the breakup biz is fun and cute until it’s not fun and cute anymore. Mel falls for a sweet, dopey, teen client played by James Rolleston, of Waititi’s 2009 breakout, Boy, in a gender-flipped side role that would usually be reserved for a ditzy blonde starlet.

“We took a premise that is quite morally ambiguous, really, and dark,” Van Beek tells Guardian Australia. “And then we really worked to make sure the film still made the audience feel warm and empowered – not grim and despondent. We pushed it toward generosity and friendship, we worked away from the darkness.”

“It’s not an anti-romantic-comedy at all,” says Sami, “because we still love the cheesiness of romantic films. But we did want to fuck with some of the tropes. And New Zealandify it as well. You couldn’t end The Breaker Upperers with a double church wedding, because people would go, ‘Oh, that’s a bit sappy, that’s a bit much, mate.’”

Fittingly, their story is bereft of the cliched female characters that Observer columnist Barbara Ellen recently described as “generic Strong Women”, or aspirational, high-achieving careerists. Instead, they are messy, everyday, imperfect women working it out together – like Abbi and Ilana of Broad City, or Leslie and Anne of Parks and Recreation, with a Kiwi goofball vibe. The comedy comes from the immaturity: the reformed nihilism of two unlucky-in-love middle-aged babies with, in Van Beek’s words, “terrible, shallow aspirations”, who finally have to grow up.

But not too much. Sami says the film is “in that same universe of awkwardness and uncomfortability” as anything by Seinfeld creator Larry David, and yet it’s also “an amplification of what New Zealanders are like. We’re self-deprecating. The joke is in not telling a joke. It’s about the delayedness. Trailing off, waffling on. There’s a lot of vulnerability”.

“Being women, just making comedy, we have an edgier style than Jemaine [Clement] and Taika,” says Sami. “We talk about masturbation and things that women just talk about on a daily basis, which we never see at the movies. It’s like the culture wants to keep women in this sacred place so that we’re easily digested and not confronting.”

Face to face, the pair are hyper-engaged and wonderful company, lobbing questions back at me. How did my last breakup eventuate? Am I on Tinder? How did the dates go? It’s that curiosity in others that makes them such switched-on storytellers. “It’s harder being the break-upper than the break-upee,” says Van Beek. “The guilt! It’s an awful thing to do.”

Their film arrives in a year of huge shifts in comedy. In Australia, the murder and rape of emerging comedian Eurydice Dixon, and the subsequent misogynist defacement of her memorial, has forced a new conversation about safety and male rage in the comedy community. And then there’s the Netflix-supported thunderstorm of Hannah Gadsby’s Nanette – an incensed standup piece by a working-class lesbian feminist, wracked with grief about the misogyny and homophobia she’s experienced – which is the biggest thing in global comedy right now.

“It’s revolutionarily good,” says Sami, of Nanette. “So many ideas in there about comedy and how it can marginalise you. It’s, like, dark as. She goes so hard, she’s spitting. I want her to be the prime minister of Australia.

“I found #MeToo quite triggering. Because you look back on your experiences and go, oh my god, that thing that I blamed myself for, no, fuck that. The culture blames us, and we blame ourselves in order not to make people feel uncomfortable. I’d internalised it. #MeToo is a problem with masculinity that needs to be fixed.”

Perhaps the same goes for comedy’s gender problem – a lot has been said about the women in comedy, and not enough about the men who dominate the industry’s boys club. Their collaborator Waititi is exemplary, they say: his films are brotherly, but never bro-y.

“There’s nothing alpha male about what he does,” says Sami, comparing the kindness and warmth of Waititi’s brand of humour with “macho” films like The Hangover.

Van Beek agrees: “Taika’s a softie.” On the set of What We Do in the Shadows, which she also acted in, Waititi and his wife brought their baby on set and sorted out “nannies and a campervan” for Van Beek’s. “I’d come out and breastfeed and then go back on set. It was such a cool thing to do.”

The Breaker Upperers has a similarly refreshing and inclusive perspective on sexuality. It’s replete with characters who are incidentally queer or trans, and yet exist without suffering plot crises of gender or sexuality: they’re just part of the fabric of the story. Sami’s character’s bisexuality, and the fact that she has absolutely no sexual chemistry with her co-star, is one such recurring gag. “We thought really early on, people will expect tension, so we have to play that joke,” Sami says. Just as Thor: Ragnarok sneakily retained the cultural identity of its Māori maker, The Breaker Upperers is a no-big-deal queer film.

“NBD queer, yeah! NDBQ,” says Sami, riffing away. “LGBTI-NBD-one-more-letter. That’s just a reflection of how it should be.” She felt frustrated with the abundance of queer and trans characters in cinema whose arcs rested on “a coming out story, or a transition story. It’s like, ‘fuck off!’ Here, they got to be closer to themselves. On one of the most heartening days on set, one of the trans girls was like, ‘It’s just so nice to be cast as someone working in a bank, and just wearing a polo.’”

It’s one more move towards a world in which queer cinema will just be cinema.

“Just like how ‘films by women’ will soon just be films,” says Van Beek.

“And,” adds Sami, “people won’t ask if women are funny anymore.”

The Breaker Upperers is out in Australian cinemas from 26 July