Prince William was one of the prime witnesses of the trauma faced by Princess Diana while she was married to Charles.
Sometimes, parents make the hard decision of going separate ways instead of raising their children in a home full of strife. The effects of growing up in a home where conflict is the norm can be long-lasting. Whether you're a royal, a celebrity, or anyone, nothing can shield your children from your marriage troubles as children are perceptive. They will listen, see, and absorb, often learning the wrong lesson from that situation. But, there are some people who turn out well even if they have witnessed a bad relationship between their parents. The parents' eventual happiness through resolution or separation may play a great hand in that.
Prince William, the older of the two Windsor brothers, was at an age where he could understand that his parents were in pain together. He witnessed their arguments, which would leave his mother in tears, and was at a loss about how to make her feel better. Often, children stuck between warring parents assume the role of making their parents happy and that is not a burden they should carry.
His parents became increasingly unhappy with each other and finally separated in 1992 and divorced in 1996. He has grown up to be a good father to his three children, a good husband, and a good person, who has followed his mother's footsteps. But, as a child, he became her support.
Royal author Katie Nicholl reveals in her 2010 book William and Harry that the young the Duke of Cambridge had once lashed out at his father after his parents were in a heated argument. "He could not bear to hear his parents bicker any longer," she said, according to the Express UK. Once, he slammed the door and charged into the garden unable to hear them go on anymore.
He was so angry at his father that he said, "I hate you, Papa. I hate you so much. Why do you make Mummy cry all the time?” He said this to his father while Diana broke down in tears again. Their oldest, even though he was only eight at the time, had known for a while that all was not right in his parents' marriage. He had become his mother's support and was often the person who would pass her tissues while she locked herself in her bedroom to cry.
This burden was taken away from him when he was sent to school at Ludgrove, which was a boys-only boarding school. Prince Charles and Diana went together to drop him at the school. Charles was wary of his wife sharing information that showed him in a bad light to the press, said Nicholl in her book.
Later, when the couple decided to go separate ways, their mother wanted to let her sons know about their decision. According to the Express UK, in documentary William and Harry: Brothers in Arms, it was said, "She made sure that the first people who found out that they were going to separate were William and Harry. She actually made the drive to Ludgrove school herself to go and tell them. Harry took it very badly, of course being younger than William, he was incredibly upset."
Nicholl also described how William reacted to the news, in the documentary. "William was pretty stoic and said to his mother well, 'if you’re happier, if you’re going to be a happier mummy, then this is the right thing to do'." As one of the supporting shoulders she leaned on, he had known her pain and only wanted her happiness.
Their relationship still affects him and he had revealed that being a dad was one of the hardest things he's ever done. "...I think when you've been through something traumatic in life — and that is like you say, your dad not being around, my mother dying when I was younger — your emotions come back in leaps and bounds because it's a very different phase of life," the duke stated, as per Insider.
References:
https://books.google.co.in/books?id=k80T7Ggu6y4C&printsec=frontcover#v=onepage&q&f=false