Singer Charlie Puth. Picture: Owen Sweeney/Invision/AP

Charlie Puth has claimed his short-lived relationship with Selena Gomez "really messed him up" because she always had someone else on her mind.

The 26-year-old singer worked with the brunette beauty on the hit track 'We Don't Talk Anymore' back in 2016 - during which time they struck up a relationship - but he has admitted it was hard to date her because she had someone else on her mind.

Speaking to Billboard magazine, Charlie said: "It's about a particular moment in my life, when someone very close to me wanted the attention of somebody else. 

"When I found that out and we ended it, I might have done some shady things too, and she might have asked me, 'How long has this been going on?'

"I don't kiss and tell, but the only way a song like that can come across as real is if there's something else going on behind the scenes. And that's what was happening.

"It really messed me up. I'm trying to put this the best way possible: It wasn't like I was the only person on her mind. And I think I knew that going in -- what I was getting myself into.

"And she evoked such good emotion on that song, it was a pleasure working with her. That's why I'm happy to sing it, even though it came from a dark point in my life."

Charlie has never spoken about his relationship with Selena, 25, before but fans started joining the dots when he unfollowed her on social media after a spat with her then-ex Justin Bieber, she never made it into the music video for 'We Don't Talk Anymore' and he used a portrait very similar to her in his 'How Long' video. 

And Charlie had every right to be cautious of Justin as Selena has since got back together with the 23-year-old singer - who she dated on and off for four years - after he reached out to her around the time she was having an emergency kidney transplant in the summer of last year due to her battle with Lupus.