Steve Perry is explaining all the ways in which Journey’s Don’t Stop Believin’ can hook a listener. “The quarters on the piano – that intro’s a hook.” He bursts into song, his alto/countertenor still distinctive at 69 years old, and he is so powerful that it is offputting: “‘Just a smalltown girl’ is a hook. ‘Strangers waiting’ is a hook. ‘Up and down the boulevard’ – hook. [His bandmate] Jon Cain thought the ‘streetlights, people’ section was a chorus. Then I turned round and said: ‘Now we need to write the chorus of choruses.’ No one knew what that meant; nor did I. But I knew we had to take it somewhere bigger and never go back to the song again. Because it had done all these things I had mentioned and, in my opinion, it needed to go one more place.”

Don’t Stop Believin’, a monster hit in the US on its release in 1981 and since championed on the TV show Glee, has been so unavoidable in the past few years that you wouldn’t guess Perry has largely been silent for 20 years, since he left Journey once and for all. There were a couple of low-key appearances on other people’s records, the very occasional interview (not a favoured pastime even when he was with Journey) and that was it. But the ubiquity of Don’t Stop Believin’ made it seem as if he was ever-present.

“I would say I was completely burned out, with touring, recording, writing music incessantly,” he says. “I was having an emotional PTSD breakdown in music. I’m not whining, I’m just saying there was a lack of connection to the passion for music I had discovered when I was seven years old. I walked away with no ideas of returning. Then, years later, things started to change.”

Monster hit ... watch the live video for Don’t Stop Believin’

Quite how things started to change, leading Perry to record his first album since Journey’s Trial By Fire in 1996, is one of the oddest, saddest stories you will hear a rock star tell.

Perry had never married. “I was too scared of it after what I watched my parents go through,” he says. “And I was around a band that went through several divorces in the course of our success. I saw them lose half of everything multiple times.” He had serious relationships – his 1984 solo hit Oh Sherrie was inspired by his then girlfriend Sherrie Swafford – but he had never been completely swept away by love.

‘I was having an emotional PTSD breakdown in music.’ Photograph: Myriam Santos

Then, in 2011, his friend Patty Jenkins, the director of Wonder Woman, showed him a cut of her TV film about breast cancer. Perry’s eye was caught by one of the cancer survivors who appeared briefly in the film. The woman was Kellie Nash, a psychologist who had undergone treatment. “I said to Patty: ‘Do you have her email?’ She said: ‘Why?’ Because she knew me. I’m not like that. I said: ‘I don’t know, but there’s something about her smile that’s killing me right now. Would you send her an email saying that your friend Steve would love to take her out to lunch?’ She said: ‘OK, I will, but there’s one thing I should tell you first. She was in remission, but it came back, and it’s in her bones and it’s in her lungs and she’s fighting for her life.’ So I thought: I’m going to forget the whole idea. I thought: you walked away from a career, your mother has passed away, your grandmother and grandfather have gone, your dad’s barely hanging on … Maybe you should just forget the whole thing. But then I thought: bullshit.”

He told Patty to send the email, the pair met for dinner and they ended up together for a year and a half.

Perry entered the relationship knowing that doctors said Nash would die, sooner rather than later. What did he hope to gain from their brief time together? “You want to know the truth? I’ve not said this to anybody yet: I believed our love would cure her cancer. I really did. We sat in our tiny apartment in New York – a very expensive small box – and she said: ‘This might take me, but it’ll never be able to touch our love.’ I never thought about such a truth like that. Not just talking about it, but physically feeling it and emotionally seeing it was new to me.”

Before she died, Nash extracted a commitment from Perry. “She said: ‘Promise me you won’t go back into isolation, because I fear it would make this all for naught.’ I said: ‘OK, I promise.’ I lay in bed thinking about what I’d just promised. She was looking at the arc of her whole life and the possibility that she may not make it had to have some goddamn meaning. She was looking for purpose in all this. I grieved for two years – it was a whole new level of broken heart. It was completely fucking broken. I worked through that and, the next thing I knew, I started writing music.”

Eighteen months after Nash’s death, Perry returned to live performance. He had been a fan of the band Eels, visiting their rehearsals, going to their gigs and joining in with Mark “E” Everett’s weekly croquet game. Finally, Everett asked if Perry might fancy joining Eels on stage. “So, we worked up It’s a Motherfucker – I love singing that – and a couple of Journey songs. And I flew out to St Paul [in Minnesota] when they were at the Fitzgerald theatre in May 2014 and jumped on stage with them. It was really a thrill. I forgot what being in front of people felt like until I went out with the Eels. Looking into the eyes of people and singing for them felt good again.”

‘Doing this has been cathartic’ ... No Erasin’, from Perry’s new album, Traces

Perry had already started writing again before Nash died, but now he started working in earnest: building a studio at his home, fetching co-writers and musicians. “I wasn’t signed to anybody. I had no management. I funded the record entirely out of my own pocket. I built my own studio. I had to have the freedom to suck – nobody was going to put their foot on the back of my neck saying: ‘Is it done yet?’” The result is Traces, an album of slick, album-oriented rock that sounds as if Perry had not taken 20 years off and for which – keeping his promise to Nash – he is putting himself out into the world, doing interviews in numbers he never did with Journey, when he was zealous about guarding his privacy.

So, how does Perry feel about his life now – not only about losing the woman he loved, but also about forcing himself to talk about it to everyone who turns up with a voice recorder? “This has been amazing. Doing this has been cathartic for me. I guess it’s time to talk, it’s time to be open. It’s time to be honest about my feelings. I think I’ve been enjoying it, because it’s been a long time coming.”

Traces is out now on Fantasy