She credits him for saving her when she was battling substance abuse.
Now, Demi Lovato and Wilmer Valderrama have decided to go their separate ways, but only as the best of friends.
"After almost 6 loving and wonderful years together, we have decided to end our relationship," both Valderrama, 36, and Lovato posted to their Instagram pages on June 3rd.
"This was an incredibly difficult decision for both of us, but we have realized more than anything that we are better as best friends.
"We will always be supportive of one another. Thank you to everyone who has offered us kindness and support over the years.
"With only love, Wilmer & Demi."
Earlier this year, Ellen DeGeneres teased the pop star about rumors of an engagement.
"I don't see a ring," Lovato answered during an appearance on DeGeneres' talk show.
"I wouldn't mind if I saw one, but there's time for everything."
In May 2015, Demi Lovato told Huffington Post Live that Valderrama stuck with her through her darkest time.
"He never takes credit for my sobriety, but I guarantee I wouldn't be alive without him today," the 23-year-old singer said.
"We're in control of what we're able to post online, and we're very open about our relationship," Lovato said.
"As I get more serious in my life, I'm more proud."
Lovato entered rehab in 2010 after allegedly punching a dancer on her tour whom she thought revealed Lovato's suspected drug use.
"Afterwards, Demi felt awful about her behavior and realized she needed to take personal responsibility for it," a family source told People at the time.
"Because of this, and because of the battles Demi has fought throughout her life, both she and her family realized she needed to take steps to get help immediately."
Lovato confirmed last year that she was diagnosed with depression and bi-polar disease.