The former One Direction star's old song recently surfaced online and on the candid number he opens up on how the person he loves the most also causes him pain.
He sings: “You know me the best but you hurt me the worst.
“Every single thing you know about me is every single thing you use to only hurt.”
He adds: “I know I should let go now (but I know, but I know), no one else feels like home, yeah.
“You know just what to say to make me stay, make me stay.
“One more dose of the pain.”
The 27-year-old pop star has been in an on-off relationship with model Gigi Hadid, 23, since 2015.
It's not known who the song is about.
However, things appear to be going well for Zayn and Gigi, as in February she hinted she'd like to start a family, as she admitted she's looking forward to her future outside of modelling.
She said: "I think that as I get older ... well one day I'll start a family and I don't know if I will always be modelling.
"I love the creative side of fashion, it's so fulfilling.
"The people I work with make me so happy, I'm so lucky to be around them. But who knows? Maybe I'll take up full-time cooking!"
Zayn was previously engaged to Little Mix star Perrie Edwards until 2015.
Meanwhile, the leak comes after the musician released the track 'Flames' in November.
The 'I Don't Wanna Live Forever' hitmaker returned to social media after a month away to announce he'd teamed up with R3hab and Jungleboi on the song.
Zayn's last studio album was 2018's 'Icarus Falls', the follow-up to his 2016 debut solo LP 'Mind of Mine'.