Fifth Harmony has one fewer note. The group announced in a message to fans that singer Camila Cabello has exited.

"After four and a half years of being together, we have been informed via her representatives that Camila has decided to leave Fifth Harmony. We wish her well,” the note read. It was signed by remaining members.

Cabello’s exit came just hours after Fifth Harmony performed at a Jingle Ball radio show in Miami, and a source told Billboard that Dec. 18, the day the split was announced, marked the conclusion of Cabello's contractual obligations to the group.

On Monday, Cabello released a statement confirming her departure and expressing her regret over how it was announced.

“I was shocked to read the statement the Fifth Harmony account posted without my knowing. The girls were aware of my feelings through the long, much-needed conversations about the future we had during tour. Saying that they were informed through my representatives that I was ‘leaving the group’ is simply not true,” she wrote.

“I did not intend to end things with Fifth Harmony this way. As sad as it is to see this chapter ending this way, I will continue to root them all on as individuals and as a group.”

The pop girl group — now made up of Ally Brooke Hernandez, Normani Kordei, Lauren Jauregui and Dinah Jane — has had major odds to defy since its inception in 2012.

They were pieced together by reality show magnate Simon Cowell on the short-lived, less successful U.S. edition of “The X Factor” after the members entered the competition as solo hopefuls. If the origin story sounds familiar, it’s because it is: Cowell created One Direction the same way on the British edition of “X Factor” in 2010.

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On “The X Factor,” viewers watched Fifth Harmony rise as underdogs to front-runners in the competition’s final weeks. They lost the series but their breakthrough positioned them as a viable entry in a pop landscape that had long been devoid of a girl group.

Early last year, Fifth Harmony released its debut, “Reflection,” which was packed with urban dance-pop and infectious throwbacks to ’90s R&B. Breakout single “Worth It” went multiplatinum and was the first single from a girl group to crack the top 20 since the Pussycat Dolls in 2009.

But like every manufactured outfit — especially pop girl groups — there were murmurs of disharmony and infighting. Fans critiqued everything from the way the women posed with each other on red carpets to how often (or not) they hung out together in off time. Breakup rumors swirled as they pursued solo interests.

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Fifth Harmony attempted to silence detractors with the sophomore effort “7/27.” Released in the spring — it’s title was the date the group was created during “X Factor” — the group members looked to show their growth. Their lead single, “Work From Home,” was a smash and they went on their first international tour this year.

In a revealing interview with Billboard earlier this year, the members appeared to be itching for more creative control — "Nobody wrote on this album,” Cabello said bluntly — and opened up about the strain of trying to make it as a group.

"I was having terrible anxiety, nonstop. My heart would beat really fast the whole day. Two hours after I woke up, I'd need a nap because my body was so hyperactive,” Cabello said. “… I was scared of what would happen to me, of the things my brain might tell me. I realized the stuff I thought was important isn't worth my health. Now I write in a diary every day, work out and meditate."

Cabello has laid a little groundwork for a solo career. Late last year she collaborated with Shawn Mendes, and their single, "I Know What You Did Last Summer," became a top-20 hit. She also appears on Machine Gun Kelly’s single "Bad Things," which just hit No. 10 on the Hot 100.

“Next year I will be working on my own music and giving you a big chunk of my heart,” Cabello wrote in her statement. “As scary as it is to take the leap, I am excited and full of joy because I know that no matter what happens, I am following my heart. I hope to see you on my journey.”

Other members have done work outside of the group, but the remaining members have vowed to keep going as a quartet.

“We are four strong, committed women who will continue with Fifth Harmony as well as our solo endeavors,” the group wrote. “Harmonizers we’re in this together.”

The Times has reached out to Cabello's representative for comment.

For more music news follow me on Twitter:@GerrickKennedy