Demi Lovato entered rehab after an overdose in July, and the singer has now completed her stay and is splitting her time between a home in Los Angeles and a halfway house.
"Demi and Wilmer are still in constant communication," the source said, adding that the two "speak over the phone pretty much every day and see each other often."
After her overdose, Lovato was hospitalized, with Valderrama reportedly visiting her there for three days in a row.
"She absolutely does not take that for granted," the source said of the actor's support. "After her last relapse, she realized how short life can potentially be and it really resonated with her that she could lose everything at the snap of a finger. One of the last things that she would ever want to lose is Wilmer."
The insider added that Lovato "never wants to jeopardize her relationship with him, her family or friends, ever again."
Lovato and Valderrama previously dated for six years before splitting in June 2016. They have remained friends since, with Lovato even posting a photo of the two in June 2017 with a caption that read, "Best of friends no matter what."
According to Us Weekly's source, a second go at romance for the pair is "definitely not out of the question."
In her 2017 documentary, Demi Lovato: Simply Complicated, Lovato explained that she knew she had personal issues she needed to work on that she couldn't properly address while in a relationship.
"The sparks never faded but there are issues that I haven't conquered yet that I know I won't conquer if I'm relying on somebody else to take care of the loneliness. I just wasn't ready and there was so much in my life that I hadn't explored yet," she said. "That was one of the reasons why we broke up because I've never been alone. It had nothing to do with falling out of love, we decided together we just probably are better as friends."
The singer continued, "I do have moments where it's late at night and I'm lonely and I wonder if I made the right decision because love is a gamble. I don't know if I'll lose him for the rest of my life. I think my heart is always with Wilmer, I think it was with Wilmer, I think it is with Wilmer, I think it will be. Because you don't share six years with somebody and not give them a piece of your heart and vice versa. I'm pretty sure that I'm not going to meet anybody that compares to him."
Photo Credit: Getty / Lester Cohen