Some more details are coming to light about the reason behind Shawn Mendes and Camila Cabello's breakup.

The couple released a joint statement regarding their split Wednesday on Instagram. 

Now, an insider close to Cabello revealed to E! News that it was Mendes who "initiated the conversation" about breaking up. 

The source claimed there was no big event that caused the split. Instead, it was a result of their relationship becoming "stale and complacent."

SHAWN MENDES AND CAMILA CABELLO BREAK UP: WE 'WILL CONTINUE TO BE BEST FRIENDS'

Camila Cabello and Shawn Mendes have split after two years of dating. (Kevin Mazur/AMA2019/Getty Images for dcp)

The insider added that the former Fifth Harmony crooner was "very upset" by the initial split but "agreed" it was an appropriate move. The first few days after the two singers broke it off were "really hard" for Cabello but she's been "keeping busy," the source said.

"She has a huge support system and is feeling renewed now," the source added to the outlet.

Cabello and Mendes announced the news on Wednesday in a joint statement shared to their respective social media accounts.

"Hey guys, we've decided to end our romantic relationship but our love for one another as humans is stronger than ever," the statement read. "We started our relationship as best friends and will continue to be best friends. We so appreciate your support from the beginning and moving forward."

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Earlier on Wednesday, Mendes was spotted grabbing coffee in Brooklyn. "He definitely looked sad. He was listening to music and keeping to himself," an insider told Fox News Digital of Mendes, who was wearing a gray coat and had his earbuds in.

Shawn Mendes and Camila Cabello pose at the 2019 American Music Awards at Microsoft Theater on Nov. 24, 2019, in Los Angeles. (Steve Granitz/WireImage)

The source relayed that Mendes was also seen the day before hitting the gym solo, running on the treadmill.

Mendes, 23, and Cabello, 24, first met back in 2014 but remained good friends until their connection turned romantic years later.

They began dating on July 4, 2019. Cabello confirmed the exact date of the relationship to a group of fans at the time.

Cabello recently shot down engagement rumors during an appearance on "The Tonight Show Starring Jimmy Fallon" in August.

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"I swear to God, I don’t know what hand the engagement ring goes on, so sometimes I’ll just, like, put it on ring finger," Cabello told Fallon after photos of her surfaced wearing a ring on her left hand.

Shawn Mendes "initiated" the conversation to Camila Cabello about breaking up, an insider claims. (Emma McIntyre/Getty Images For dcp)

Fox News has reached out to the singers' reps for comment.