Article continues below advertisementOK! can reveal King Charles has quietly resigned himself to what he sees as one of the great failures of his life, accepting the public story of his marriage to Princess Diana will never fully reflect his own view of what went wrong.The now 77-year-old monarch's 15-year marriage to Diana, who was 20 when they wed in 1981 and 36 when she died in 1997 in a Paris car smash, remains one of the most scrutinized relationships in modern history.