Not quite like that. Charles actually proposed to Camilla before he went off to do his Naval tour. She turned him down because she'd been warned off by Earl Mountbatten, who at that time was quite determined to see Charles marry his granddaughter Amanda Knatchbull. Mountbatten, whose influence on the Royal Family was disproportionate, made sure that Camillas' family married her off as quickly as possible while Charles was gone Then Mountbatten was killed, Amanda turned Charles down and the ambitious Spencers pushed Diana at him. Charles was under pressure to marry and breed, so that's how it came about.