Olly Alexander has spoken about a relationship he had with a straight-identifying man.

Fans were ecstatic when Years & Years finally released their long-awaited comeback single Sanctify earlier this year, and the band’s frontman Olly later revealed it was about his feelings for a straight guy.

“I’m feeling like both a sinner and saint or a devil and angel, leading this guy down a path of ‘sinfulness’ while, at the same time, helping him explore his sexuality,” he told Nylon of the song’s meaning last month.

Now, during an interview with BBC News, the 27-year-old singer has elaborated on the almost-relationship.

“He told me he was straight and we became friends, and at a certain point the relationship tipped over into something more intimate – and it felt like we were becoming lovers,” Olly said.

“And suddenly, there was just an explosion of pain and conflict.

“I’ve been out as a gay guy for nearly 10 years, and I know how that journey of coming to terms with your own identity can be really painful.

“I wanted to write something that spoke to that experience.”

Elsewhere in the interview, Olly spoke about his ideal relationship setup, joking: “What I think would suit me was if I was in a thruple and the other two guys lived in a house nearby.

“I could visit them every now and then and they’d cook me dinner, and then I could just go home and watch TV by myself.”

Sanctify is the lead single from Years & Years’ forthcoming new album Salo Panto, which serves as the follow-up to their chart-topping debut Communion. It’s due out 6 July, and will be accompanied by a short film narrated by Judi Dench.

Last year, Olly revealed that he was advised to not talk about his sexuality during the band’s early years.

“I kind of had one media training session early on with this woman who kind of advised me not to come out,” Olly admitted. “‘You don’t need to – you don’t need to make it a big deal. Why should you have to express your sexuality?’

“I can see where she was coming from, and I understand why that might have been the norm to tell musicians in the past.

“After a certain point I realised I was getting this real anxiety and stress from worrying about what interviewers might ask me. I felt like the music was about me and my identity, so it didn’t make any sense for me to not talk about this.”

Olly added: “I made the decision – it did feel like a bit of a choice – really, really early on that I’m just going to be out as much as possible.”

Last summer, the singer launched a new LGBTQ documentary, Growing Up Gay, for the BBC, which can be streamed on the iPlayer now.

Related: Olly Alexander interview: Being bullied at school made me ‘hope I wouldn’t turn out to be gay’