The fight was about what tiara Meghan could wear at the wedding.
Meghan eventually ended up wearing a diamond and platinum tiara from the Queen's collection.
When Harry got worked up when his sweet princess didn't get what she desired, the Queen had to step in and is quoted saying: "Meghan can not have whatever she wants".
"Melissa is a hugely talented person", the source is quoted as saying.
Kensington Palace declined to provide a statement as to why Meghan's PA had left so suddenly, however they did offer a tribute to the aide saying that she would be missed.
The departure of her personal assistant, known only as Melissa, has come as quite a shock to the Palace, it is claimed.
Bride-to-be Markle wished to wear a tiara with emeralds but was refused after its origins could not be established. "There were concerns it could have come from Russian Federation originally".
Meghan brushed her long dark hair to one side, displaying her dewy pregnant glow and glossy pout.
To which William added: "I know, I've got serious OCD on light switches now, which is bad".
This was the Queen's 73rd Remembrance Sunday service - her second time watching from the balcony.
She will soon be joined by the royal couple's private secretary Samantha Cohen, who follows predecessor Edward Lane Fox out of the door.
Speaking about his father in the doccie, the Duke of Cambridge revealed that he would like the Prince of Wales to spend more time being a grandfather rather that working, E!
Apart from this, the Royal Family members also had an issue with the way Meghan treated the Royal staff.
Despite the rules, the expecting mom is "determined to do things her way", said the source.