they met in 1970 and started a relationship, not exactly like the Edward and Wallis debacle. he goes off into the Navy, she marries, he then gets together with Diana, then goes on to have affair with Camilla five years later, according to various sources. He could have shown more metal had he said he wanted to marry Camilla early on, perhaps he didn't want to,
sowing wild oats and all that, but to marry someone knowing you care for someone else, that does seem quite cruel. Diana was so very young as well, and as you say it could have all been so different.