Your children not being "yours" - even if you stay in the marriage/stay in the, (for many women marrying a royal), foreign county.
How about this - some quotes from a book I'm reading about the Monaco family -
About Grace: "Many days were spent in boredom."
Her lady-in-waiting is quoted as saying "I had to get used to it" - when talking about Grace taking to her bed in the middle of the day due to her despair over her life in Monaco.
A visitor to the Palace is quoted, saying how Grace "hissed" at him when he accidently stumbled upon her playing with Albert in one of the courtyards. She mistakenly thought her son was being taken from her again.
(Albert was trained to turn to his father for comfort, advice, guidance and to not depend on his mother.)
Grace worked on being a Princess. She had the insight, for example, to study Royalty of the past, and realise the "power/prescence" bestowed by their high/big hairstyles.
(That is where Grace got her ornate and intricate hair inspiration from.)
So she didn't give up, but what a price they all pay, at a personal level.
Even Caroline was quoted last year, saying she and her brother were closer to the nanny than their mother.
This book is full of "the scales falling from your eyes" moments about such a life.
I could quote about Lord Snowdon's experience when he married Princess Margaret, what marrying the Queen cost Phillip, and so on.
The personal cost can't be repaid by getting to dress up and live your life in nice rooms.