A source close to the engaged couple tells PEOPLE that the actress, 37, and actor/musician, 33, “had yet another big fight” and that “it’s always the same thing.”

“They have severe trust issues in the relationship. It’s been rough, but [they’re] still trying to work through it,” the insider adds.

Says another source who knows the pair, “They’re still on and off.”

Reps for Fox and Kelly did not immediately respond to PEOPLE’s requests for comment on Tuesday.

Megan Fox and Machine Gun Kelly in Los Angeles on Feb. 5, 2023.

LESTER COHEN/GETTY

Fox and Kelly, whose real name is Colson Baker, first sparked romance rumors in May 2020 after they were spotted spending quality time together, and got engaged in January 2022.

However, the pair hit a snag in their relationship this past February when an insider told PEOPLE that they “had a fight over the weekend,” and that Fox was “very upset” and refused to “speak to” Kelly. She also posted cryptic song lyrics to her Instagram before deleting her account.

By June, the Midnight in the Switchgrass costars had seemingly ironed out their issues, with a source telling PEOPLE that Fox was wearing her engagement ring again.

“They have done a lot of work to make their relationship strong again and are back together,” the source said. “They are engaged, but are not wedding planning.”

“She seems much happier,” the insider added.

Machine Gun Kelly and Megan Fox in Las Vegas on May 15, 2022. MATT WINKELMEYER/GETTY

Last month, the couple stepped out for a date night at the GQ Men of the Year Party, just over two weeks after they attended a Casamigos Halloween party in L.A. dressed as Kill Bill characters.

The GQ outing came a week after Fox published her new poetry book, Pretty Boys Are Poisonous, and highlighted the support she received from her fiancé throughout her writing process.

“I think it helps that he’s an artist himself and recognizes that he has this outlet where he gets to experience his catharsis through songwriting — where he gets to express his pain in that way,” the Expend4bles actress explained on The Drew Barrymore Show.

“As an actor, you don’t really have that, because I’m reading someone else’s dialogue. So I don’t really get to go to work and put my experiences and my pain into my art,” Fox continued. “So he recognized that I needed an outlet for that, and when you love someone, you’re not gonna deny them their right to experience a relief from their suffering.”

“And I think that’s just what it is to care about someone and to want to see them heal,” she added.