Scott Disick and Sofia Richie have reportedly split after being together for three years.
It is claimed their romance has sadly "run its course" as a source allegedly claimed Sofia is "fed up" with Scott's behaviour.
The pair's relationship hit headlines when they began dating three years ago due to the 16 year age gap between them.
Kourtney Kardashian's ex Scott is 37, while model Sofia is 21.
It has also been claimed that Scott's close relationship with Kourtney wore Sofia down as he shares kids Mason, 10, Penelope, seven, and Reign, five, with his ex.
A source told Page Six: "Kourtney didn’t make it easy for her and you can only tolerate that kind of treatment for so long."
The source added: "Scott had gone back to his old ways and Sofia got fed up."
Scott and Sofia began dating in 2017, after he split from Kourtney, 41, in 2015.
The reality TV star was checked into rehab during lockdown in April but checked himself out a few weeks later.
Scott has been very open in the past about his substance abuse and struggled to cope with the grief of losing both his parents at a young age.
It is reported that the pair are spending the coronavirus pandemic lockdown separately.
The star celebrated his birthday this week and Kourtney's entire family showered him with sweet birthday messages.
Kourtney's mum Kris Jenner even went as far as to hint that she wants them to get back together.
Kris took to social media on Tuesday evening to pay tribute to Scott on his 37th birthday as she made the comment.
Appearing to suggest that she is still holding onto hope of the couple once again becoming romantically involved, she showered Scott with kind compliments via her Instagram stories and sharing a throwback snap of Kourtney and Scott.
The black and white photo showed Scott with his arm wrapped around Kourtney's neck as they posed alongside Kim Kardashian and her husband Kanye West.