Demi Lovato and Wilmer Valderrama announced the end of their six-year relationship in matching Instagram posts on Friday.
The pair said the decision had been "incredibly difficult" but they would be "better as best friends".
Cool For The Summer singer Demi and That '70s Show actor Wilmer started dating in 2010 when Demi was 18. Shortly after she entered rehab for "physical and emotional issues".
Last March she shared an image of the two kissing to mark three years' sober and thank him for "supporting my recovery".
She captioned the picture, "I wish I could put into words how grateful I am for this man right here...I really wouldn't be alive today without him. I love you Wilmer."
Wilmer, 36, and Demi, 23, were last seen together publicly on the red carpet at the Billboard Music Awards in LA on May 22.
Demi shared a loving post celebrating their six year anniversary in January this year and the two are very open about their love for one another, with Demi stating only early this year she would like to marry him.
She is due to start a tour of the US with Nick Jonas later this month.
It follows a week of celebrity break-ups that include Taylor Swift and Calvin Harris, and Zayn Malik and Gigi Hadid.