Don't forget, Charles also dated Diana's elder sister for a while.....but it seems that Tim may feel somehow let down when he discovered that the Charles-Diana romance was not a fairy-tale romance novel. Now, obviously I wasn't intimate friends with either Charles nor Diana, nor privy to exactly what was discussed or developed during their courtship. But we now have enough information from many who were involved to be fairly certain about a few facts.
Charles was under intense pressure to choose a bride, and his beloved Uncle Dickie had been advising him on the choice, strongly lobbying for his own granddaughter the Hon. Amanda Knatchbull.. In Aug 1979, Uncle Dickie was assassinated and shortly after, a distraught Charles proposed to Amanda. When she declined, Charles had to start over. 8 months later he was reacquainted with Lady Diana Spencer, who happened to fit all the Mountbatten criteria: English, aristocratic, a virgin, Protestant, attractive and sweet-natured. The fact that Charles had virtually nothing in common with her, nor gave not the slightest outward indication of being in love with her, did not appear to factor into the decision. That summer and fall he shopped Diana around to the Royal Family to obtain their reaction to her as a potential consort, and received mostly positive feedback. He proposed in Feb 1981 - just slightly more than a year after having proposed to Amanda.
At the time it was easy to dismiss Charles' apparent indifference to Diana as just being "British reserve". But one need only watch Charles and Camilla interact with each other today to see what Charles looks like in love. Diana was no fairy-tale romance - she was a business transaction. Not that I necessarily blame any party - they were all products of their respective upbringing.