A third member of Meghan Markle's private staff has resigned.

Amy Pickerill announced she is stepping down as Markle's assistant private secretary once Markle and Prince Harry move to Frogmore Cottage later this month, Daily Mail reports. She is reportedly moving overseas following the termination of her post.

"Amy is leaving," a royal source confirmed to the outlet. "It’s very sad for her colleagues, as she is a really popular member of staff."

Pickerill was appointed to her post just last year and has often been referred to as Markle's "right-hand woman" as she is always by the Duchess' side. Daily Mail's royal correspondent Rebecca English tweeted that Pickerill told Markle of her plans to leave her position at Kensington Palace last year but only recently finalized the decision. 

She will be the fourth key member of Markle's staff to leave within a year, raising questions as to why so many of her close staff are taking off. 

So who is Amy Pickerill and why did she quit? Here's what we know so far. 

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1. She was Markle's assistant private secretary.

Pickerill assisted Markle with her transition into the Royal Family and has been by her side as she learned the ins and outs of Kensington Palace and her new role as Duchess of Sussex. Her duties are widespread, but she mainly manages Markle's schedule and handles official correspondences, Business Insider reports. Pickerill is also in charge of preparing Markle's briefs before her engagements as well as the Duchess' diary.

Daily Mail

2. There are no hard feelings between Pickerill and Markle.

Although the exact reason for Pickerill's departure is unclear, she and Markle are close and do not have a negative relationship, a Kensington Palace source told Harper's Bazaar.

"Amy is leaving after the arrival of the baby," the source said. "The Duchess will be very sad to see her go, but is excited for her as Amy has exciting plans ahead including spending some time abroad. Amy had originally planned on staying until at least the end of the year, but with the baby coming it makes sense to help recruit someone now who can pick up when The Duchess returns to her official work. They will definitely stay in touch and Amy will be on hand for any advice and help that is needed in the future."

She plans to continue being a part of Markle's life, just not as her employee.

“They will stay in touch and Amy will remain as a personal adviser to her in the longer term. They are very close,” a source told PEOPLE. “It is very amicable.”

3. She wants to make sure Markle is comfortable with her new baby before she leaves.

Pickerill wants to make the transition as easy as possible for Markle, an insider explained to Daily Mail.

"She has agreed to stay on to help them with the birth of the baby and organize their new household, but will then move on," the insider said.

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4. She joined the Royal Famly in 2016.

Pickerill became a part of Prince William and Kate Middleton's team in September 2016 when she was hired as a senior communications officer. After serving the Duke and Duchess of Cambridge for over a year, she was personally chosen to work with Prince Harry and Markle, Metro News UK reported.

Prior to working for Kensington Palace, Pickerill was a media relations manager and in the press office of Royal Bank of Scotland and held a position in public relations at Ogilvy, according to her LinkedIn page.

5. She is the fourth assistant to quit on Markle's watch.

Since Markle became a part of the Royal Family, four of her close staffers have quit.

On top of Pickerill's resignation, Markle's bodyguard ended her employment with the Royal Family in January. The private protector was not named but was an officer with the Scotland Yard police and called it quits after just six months,

The Duke and Duchess' private secretary also announced she will be leaving once their baby is born. Samantha Cohen, who has been with the Royal Family for 17 years, left her position as Queen Elizabeth II's private secretary in 2017 to be a part of Markle and Prince Harry's staff. News of her resignation broke in December, just a month after another one of Markle's assistants quit.

In November, Melissa Touabti ended her employment with the Duchess, less than six months after she married Prince Harry. She managed Markle's schedule and played a key role in planning Markle's wedding to Prince Harry.

Rumor has it that Markle has earned the nickname "Duchess Difficult."

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Sarah Gangraw writes about all things news, entertainment and crime. You can follow her on Instagram and Twitter.