The 38-year-old actor was shocked when he heard that his ex-girlfriend - whom he dated for six years until their split in June 2016 - had been rushed in to Los Angeles' Cedars-Sinai hospital in California earlier this week following a suspected overdose.
And, although they're no longer an official couple, the hunk hasn't wanted to leave her side since and has been keeping her company while she's monitored by doctors.
A source told PEOPLE.com: ''Wilmer has spent hours at the hospital with Demi every day. He seems very concerned about her.''
And it seems his support is helping her through her ordeal as a friend of the 25-year-old singer has said she's getting better every single day.
The insider explained: ''She's resting and getting better in the hospital. Her whole family and Wilmer are just there to support her through recovery.''
It was previously claimed Wilmer had been left ''shocked'' by the 'Skyscraper' singer's hospitalisation because he's seen her go through many ups and downs before.
A source previously said: ''He knew she was going through a tough time but he wasn't prepared for this.
''He saw her through so many ups and downs and was her rock through some of her darkest moments. To see her back in such a sad and vulnerable place is heartbreaking for him.
''He always cared deeply for her and they truly remained friends after they broke up.
''Demi always hoped they would end up back together in the future. He's the love of her life and vice versa.''
Meanwhile, it has been reported that Demi - who publicly revealed she'd relapsed in her addiction battle with her new single 'Sober' last month - fired her sober coach, Mike Bayer, just three weeks before her suspected overdose.
'Devour You' is a fantastic follow up to Starcrawler's debut album and represents a move on in terms of sound and, in part, direction.
Salvation Jayne's third birthday bash was a riot of colour and a celebration of a band very much enjoying what they do.
We're feeling the nostalgia this month.
American Thighs was released on this day in 1994.
Gloo is a new supergroup consisting of UK mystic-beat producers Iglooghost and Kai Whiston as well as nu-pop singer/producer BABii.
Listen to her new single Forgive Me now.
His new album Underneath It All is out now.
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