The actress and musician began dating after meeting on the set of ‘Midnight in the Switchgrass’ back in March 2020

Megan Fox and Machine Gun Kelly’s relationship continues to be bumpy, a source close to the couple tells PEOPLE exclusively.

“One day they’re up, the next they’re down,” the source says.

The couple, who began dating in 2020 after meeting on the set of Midnight in the Switchgrass, have previously shared how intensely their relationship started.

“I didn’t know what [love] was until me and her made eye contact,” Kelly said. “That’s when I was like, ‘Whoa,’ ” Kelly (real name Colson Baker) said on The Howard Stern Show back in September 2020. During that interview, Kelly said it was love at first sight, adding, “I did fall in love for the first time.”

In November 2020, Fox said they had a connection of “mythic proportions” and “loving him is like being in love with a tsunami or a forest fire.”

They announced their engagement in January 2022 and sealed their union by drinking each other’s blood.

“That intensity is still there nearly four years into their relationship, but that’s not necessarily “healthy,” the source says.

Megan Fox and Machine Gun Kelly attend the Pre-GRAMMY Gala & GRAMMY Salute to Industry Icons in 2023.

KEVIN MAZUR/GETTY IMAGES

“There are still a ton of trust issues between them and it’s very toxic,” the source concludes. They can’t stay away from each other and there’s a lot of history there, but they also don’t know how to be in a healthy relationship,” the source explains. “They’ll be totally fine, then days later get into a huge blowout fight and not talk for weeks, but then give in and be all lovey-dovey again.”

Fox, 37, confirmed their engagement was called off some time in 2023 while appearing on the Call Her Daddy podcast earlier this week.

“You got engaged and I think it got called off…how would you describe your relationship with MGK?” asked host Alex Cooper.

“As of now I don’t have a comment on the status of the relationship per se,” Fox replied. “What I can say [is] that [he’s] what I refer to as being my ‘twin soul.’ There will always be a tether to him no matter what. I can’t say for sure what the capacity will be, but I will always be connected to him somehow.”

“Beyond that I’m not willing to explain, but all those things you said were accurate things that have occurred,” the Jennifer’s Body actress responded.

Megan Fox and Machine Gun Kelly attend the 65th GRAMMY Awards in 2023.

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The source confirms the engagement plans were called off.

“They never picked back up wedding plans or even got to a place where they could think about really getting married,” the source said.

“It doesn’t seem like either wants to give the other up, even though they both know it’s not healthy,” the source concluded.