Dressed in a sharp grey suit and crisp white shirt, Spike Jonze does not seem properly attired for a one-man food fight. But 20 minutes after he sits down across the table from me, he plunges his head into lunch. He's polite about it, of course: "Do you mind if I put my face in my food?" he inquires, pre-dive.

Up close, the director of Being John Malkovich and Adaptation looks a good deal more boyish than his 44 years. Doubly so when he emerges from his salad with a goofy grin and bits of lettuce and shrimp attached: "Where was I?"

The punchline to this tomfoolery is that Spike Jonze has just made the most mature, achingly romantic film of his career. Her, as audacious a cinematic dissection of love as we have seen since Eternal Sunshine of the Spotless Mind, traces the relationship between sad-sack writer Theodore (Joaquin Phoenix) and Samantha, his computer's intuitive operating system, as voiced with foxy aplomb by Scarlett Johansson.

It could, one feels, have belonged to the same unlovely subset of man-machine interfaces as S1mone. Instead, it's a cerebral, full-blown weepie, an ideal date movie – released here on Valentine's Day – and an even better break-up picture. Basically, it's writer-director Jonze ripping out your heart and stomping on it forever.

“Oh good,” says Jonze. “I’m very sorry to have done that to you. But good, right? That is something. Break-up picture? Wow. What do you think would happen? How would that night go?”

There is more to Jonze's conceit than mismatched or star-crossed love. Theodore romances Samantha in a sphere of corporeal and potential partners that includes supporting cast members Amy Adams, Rooney Mara and Olivia Wilde. It's a world where everyone is perennially plugged in at the expense of human interaction. Is this the same dystopian postal code of the Jonzeiverse where he placed Arcade Fire for the 28-minute promo for Scenes from the Suburbs?

“I don’t think that the distinction between utopian and dystopian is a black-and-white distinction,” says the film-maker. “We could have sat here in this exact hotel room 100 years ago and had a talk about 2014. And depending on how you editorialise it could sound dystopian or utopian. The future is subjective. What’s relevant are the choices we make and how we find happiness in whatever context we find ourselves. For us, when we were designing this movie, we weren’t trying to design the future. We were trying to sense of the feelings we have right now. Whatever those are. And um…”

He pauses: “I have feelings about this. But they’re super-complex. I guess I’d rather just leave the movie with people and let them have their own experience with it. I try not to be judgmental as a person. That doesn’t mean I don’t judge things. But I try to look at things from as many different angles as possible. It’s the same thing when I’m making films.”

Her, accordingly, is a deceptively deep piece of cinema and one that demanded tough love. The editing process was lengthy and required the assistance of fellow auteurs Steven Soderbergh and David O Russell. More traumatically, there was a personnel change at the post-production stage. The role of Samantha, which had been played off camera and recorded with Samantha Morton, was recast. It's a lucky break for Scarlett Johansson, who, ironically, has never been sultrier than as Her's disembodied, souped up Siri-clone. But it can't have been easy to let go of Morton, who gave her name to the character and who retains an executive producer credit on the finished film.

What happened?

“Um. I’m going to put my face in this food again,” he sighs. “I’m hesitating. Because I’ve talked about this so many times it’s starting to feel insincere and it’s not insincere. Um . . .”

You want me to just get the answer online?

“Could you? That would be so great. No. I’ll say it. I love them both. And they both contributed a lot to the movie. There! Um.”

Today, Jonze is a little hoarse and keeps apologising for his jet-lag. But he looks a lot less careworn that he did when we met after 2009's Where the Wild Things Are debuted with an underwhelming box office take and a raft of puzzled reviews. That film, a $100 million adaptation of Maurice Sendak's classic picture book, represents Jonze's first dalliance with Hollywood proper. It was not, he recalls, a particularly happy experience.

“I didn’t really mind that people were upset that the film was scary and that it wasn’t for children and that it was supposed to be a family film,” says Jonze. “How I measure success or failure is by how close I got to the intention behind it when I made it. And I set out to make a movie about what it’s like being nine years old and trying to navigate the world and how scary it can be. I wanted to make a poem about being scared. Because the book was a poem. And I felt I was true to that intention.”

But the negative notices must have felt like a kick in the teeth, surely? Tellingly, Her arrives some four years after Wild Things.

“It’s interesting that you think of it that way,” says Jonze. “But I didn’t think of it as a kick in the teeth at the time. I feel like none of my movies are universally loved. That one was different because it was expected to be something else. So for me the only unexpected thing was fighting with the studio. Because that was tiring. So I took a year off making short films and short projects before I had the energy to go write.”

It's hardly surprising that Jonze retreated into short-form. Adam Spiegel – as it reads on his birth certificate – first came to our notice as the hot-shot video director behind the promos for Weezer's Buddy Holly, Bjork's It's Oh So Quiet and the Beastie Boys' Sabotage.

"I never really thought I was going to be a film-maker," recalls Jonze. "There were always movies that I loved. I loved Star Wars. I loved The World According to Garp. Which I saw when I was really young for some reason. I loved Being There. I didn't totally understand those films. But I related to them. I saw Being There at 19. And it was unlike anything I'd ever seen. Time Bandits too. It felt like something I'd never seen before but also super familiar. Like me in my bedroom by myself playing for hours. Looking back those movies became a part of me being a film-maker. But I had no awareness of that for a longest time. I didn't ever think I'd make films. I thought I'd be a photographer for skateboard and BMX magazines."

During the 1990s, Jonze and fellow wunderkinds Chris Cunningham and Michel Gondry were high rotation MTV fixtures. I wonder how he feels now that music television isn't quite so musical.

"But I think the medium is coming back despite that," says the film-maker. "And I think it's back in a really cool way. YouTube has totally revitalised the form. Look at what Romain Gavras and MIA are doing. The Bad Girls video is as good as any video that's ever been made. Look at Flying Lotus. Kanye did Runway. Dirty Projectors did this 30-minute film that was really abstract and interesting. It's different obviously. The 1990s had MTV and that kind of focused it in a way. But now that were no longer watching 15 channels it was never going to be that focused. And whatever you're interested in, you can find some amazing and creative things online."

Jonze remained a constant presence on MTV, even during the leaner, reality TV years, as the sometime star and producer of Jackass. Indeed, he shot Her while simultaneously writing and producing Jackass: Bad Grandpa. While it's true that Her's lovely brand of melancholy is frequently punctured with humour, it's never exactly Johnny Knoxville in geriatric make-up. I wonder if Jonze can place his comic sensibility? Because nobody else can.

"I'm not snobby at all," he shrugs. "I love Louis ck. I think he's a genius and one of the best writers around. I loved 21 Jump Street because of what Channing Tatum and Jonah Hill did with it. They took something that you went in thinking: I'm kind of tired today and I just want to go see a fun movie. But at every turn they went a smarter funnier way. Charlie Kaufman is one of the greatest writers. Jon Stewart. Will Ferrell. I could go on and on. And Jackass. Because nobody thinks we're funnier than we do. We have so much fun shooting it. And then were cracking up in the editing room. That's why I keep doing that stuff. Because going to the office and coming up with ideas means laughing with your friends. And it feels good to really laugh with your friends and to crack each other up."

It’s not just the rock-star chums. There is something achingly hip about Jonze. Just don’t use the word hipster around him.

“What does it mean?” he cries.

Hmm. I was going to ask him. Isn’t he supposed to be one?

“I know! But I’m just doing what I’m doing. I like these shoes. Are they hipster shoes? Should I be worried?”

Okay. Granted, it's a semantically unstable term. But the safety pin tie and high-waist pants and rolled-up sleeves that Joaquin Phoenix wears in Her. Those are accessories one might look at and think 'hipster'.

“Oh my God. You are possessed! You have oral piercings. People must call you a hipster all the time.”

Yes. But nobody knows who I am. And I don’t care.

"Exactly, right? I think there's something really marginalising about that word. When we made Where the Wild Things Are, we thought of it as this very personal film. And then people called it a hipster children's film because I worked on it and Karen [O, from the Yeah Yeah Yeahs] did the music. I feel like that's so inaccurate. Karen is an artist. What she does with her band is so emotionally raw. Hipster sounds like you're doing something for effect or to be ironic. And there's no one less ironic and less affected than Karen. I remember in the 1990s making music videos. And people said they were ironic. And I used to think 'no. You can be playful and self-aware and funny without being ironic. I'm being genuine here. This is me trying to make sense of this insane experience of being alive."

He laughs: "I mean it. I mean it all."

yyy Her opens next Friday