Rivette Diana Mountbatten-Windsor of Sussex turned one on Saturday of the Queen's Jubilee weekend, and her parents, Prince Harry and Meghan Markle, threw her a lovely birthday party at Frogmore Cottage in Windsor. They also very graciously shared adorable photos of the little girl with all of us to mark the occasion.

But the day was not all sunshine and rainbows: according to one source close to the Duke of Sussex, of those who were unable to attend, it was Prince William and Kate Middleton's absence from the party that caused the deepest grief.

"It was a toothless remark that the Cambridges did not attend," the source told Heat. For Meghan, it only strengthened her resolve not to come back."

As previously reported, the Cambridges were scheduled to visit Wales beforehand and could not skip that visit. A source told "Entertainment Tonight" after the Jubilee, "It's just a coincidence that it happened on the same day. It was not meant to be taken lightly."

Nevertheless, knowing how strained the relationship between the two royal couples has been since the Sussexes left their royal duties in early 2020, it is easy to hypothesize that the Cambridges did not want to attend either, even if they were physically unable to attend. That would be a real challenge.

The reception of the two by the entire royal family was chilly at best. Harry and Meghan knew it was going to be awkward, but they had no idea how hostile the reception would be."

They added, "It was very hard for Harry to be ridiculed like that."

"He tried not to read the negative things written about them, but he couldn't avoid it. They have been accused of exploiting their fame and being greedy for money. There has been a lot of applause for them, but they know that there is a public that does not want to come back for the Jubilee and that has really hurt them"