Over the past few months, Prince Harry and Meghan Markle have chosen to live a low-key lifestyle in the U.S. after their official split from the royal family last April. 

Following their bombshell decision to step down from their roles as senior royals, the Sussex couple and their 1-year-old son Archie is now living in a rented $18 million hilltop mansion in Beverly Hills, which was reportedly owned by media mogul Tyler Perry. 

Meghan Markle Jealous Of Kate Middleton

However, the runaway duchess is being haunted by her past, as one royal author claimed that the 38-year-old former actress is "very sensitive" about being "number two" to her sister-in-law Kate Middleton. 

According to Daily Star Online, royal author Tom Quinn mentioned that Meghan had an argument with one of Kate's staff after they turned down her request. 

"It was almost as if in that one encounter, it encapsulated for Meghan the problem that she had, that she's a Princess and she's number two," a source told the author. 

Quinn, who had just released a book titled "Kensington Palace: An Intimate Memoir From Queen Mary To Meghan Markle," added that the incident happened when the Duke and Duchess of Sussex were still living in their Nottingham Cottage at Kensington Palace.

Tor recall, Prince Harry and Meghan officially moved out of their residence at Kensington Palace and transferred to the two-story Frogmore Cottage at Windsor, months before Meghan gave birth to baby Archie. 

The Cambridges, on the other hand, were staying in the spacious Apartment 1A, which was used to belong to Princess Margaret.

Moreover, the royal author went on and revealed that being rejected by her sister-in-law's staff made Meghan left like "she had been put in her place."

"She's very sensitive about not being treated with the same respect that she feels Kate is, so can react badly and doesn't take it lying down," Quinn added.

Quinn also pointed out that the alleged row between the former royal and Kate's staff left the future Queen consort "horrified."

Meghan Markle And Kate Middleton's "Tights" Situation

In previous royal family news, society bible Tatler magazine cited that the two duchesses had a fiery row during Meghan's 2018 wedding, which took place at the historical St George's Chapel at Windsor Castle. 

According to the publication, the incident happened during the wedding rehearsal when the bridesmaids -- which included Kate's only daughter Princess Charlotte -- should wear tights.

"It was a hot day, and apparently there was a row over whether the bridesmaids should wear tights or not. Kate, following protocol, felt that they should. Meghan didn't want them to," the source told Tatler's Anna Pasternak. 

The publication also cited that Duchess Kate -- who usually follows royal protocol -- "felt that they should" have the bridesmaids wear tights. However, "Meghan didn't want them to" and that rhe photographs suggest that Meghan won."

Another controversial scandal exposed in Tatler's July/August issue titled "Catherine the Great" was that the 38-year-old royal mom was left "exhausted" as a result of Prince Harry and Meghan's decision to leave the monarchy. 

READ MORE: Prince Harry's Pain: Meghan Markle SUFFERING Big Time With This!