According to a source, their romance "started going downhill" in the weeks before her fiancé traveled to Atlanta, GA. to film a new project. The source reveals, "They were arguing a lot and Demi didn't want him to go without her."
E! News reported in mid-September that the star traveled to Atlanta to be close to him while he worked, but the source shares, "There has been a lot of tension and Demi left him to get a clear head."
In addition to their arguments, the source says the singer realized "she didn't know who Max truly was and didn't think he had good intentions."
"There were many red flags she was ignoring and trying to turn a blind eye to," the insider explains, with a second source adding, "She doesn't trust him and thinks he's sketchy."
The second source adds that the artist "feels he proposed to get attention." Max popped the question nearly four months after their relationship began in March.
The doubts Demi had about his intentions were likely intensified by the concerns of her mother, Diana De La Garza, and close friends, who the first source says were "warning" her about Max. The source explains that they believed it was "best" for Demi to end her relationship with the soap star "sooner than later."
And though there are questions about the sincerity of Max's feelings, the source says there is no doubt that Demi "really loved him and wanted it to work."
"Demi is really upset and distraught about it," the source adds.
Nonetheless, the source says she's asked her now-ex to get his belongings out of her house, which they began sharing shortly after they started dating earlier this year.
As the singer works through the breakup, the second insider confirms she's returned to Los Angeles, where her family has "rallied around her."
Max and Demi have yet to comment on their split.
Earlier on Thursday, Max took to Instagram to promote his new film, telling fans that he's "so excited for my movie to come out next year."
Meanwhile, Demi's close friends and family have already unfollowed the Lifetime star on social media.