I think it is more of a question of should he have
been allowed to marry Camilla earlier and the answer is yes. But royal heirs weren't allowed to marry young woman of a certain reputation (whatever that really was) at the time so a suitable wife was found for him. He couldn't even bring himself to say that he was in love with Diana at their engagement and he never brought himself to the marriage since his heart was already spoken for. A bit unfair, IMO.
It wasn't really about Diana. Since he couldn't originally marry Camilla, I don't think Charles really cared who he married as long as she fawned over him or a better attempt would have been made to find someone of a suitable pedigree that he could have more in common with and fall in love with. There were no shortages of available foreign princesses and noble British ladies at the time.