I disagree there is nothing romantic or loving about their relationship, it was pure selfishness.
If, as they have said, they always knew how they felt about each other, then neither of them should have married other people.
Once they brought other people into the mix as spouses, they became common adulterers. They made vows in front of God that they broke. Charles never intended to keep the vow. Camilla may have intended to keep hers at the time of her marriage, but she has said she became engaged to her first husband to make Charles jealous.
Charles socially and militarily outranked Camilla’s husband putting him in the position of acquiescing to his wife’s affair to hang onto his position and rank or losing it all if he exposed the Prince’s behavior with his wife. Diana I think was always wobbly emotionally, but was chosen for her good breeding and youth. She had the starry eyed notion that she was the fairy tale princess and others made her dream seem real.
I view them as immature and spoiled. Their selfishness wrecked many lives including their children’s.
If I was British, I’ll vote to dismantle the Royal Family. It’s absurd to be paying people to play aa a Queen or a King, Princes and Princesses. They all need to be productive and actually contribute something to society.