The real reason King Charles didn't marry Camilla when he first met her revealed in new documentary

LOS ANGELES -- Imagine the royal family without a Princess Diana. Without a Prince William or Harry. This could have been a reality.

Decisions have consequences. It's a lesson a young Prince Charles learned early in his royal life. And one decision could have changed the entire makeup of the monarchy. Prince Charles did not marry Camilla Parker Bowles when he first met her.

Why? The answer is in a new documentary called "Charles: In His Own Words." It takes a look at the life of His Majesty King Charles III using archival footage and photos. Filmmaker Tom Jennings spoke with On The Red Carpet.

"He met Camilla in 1970," Jennings said. "They were dating when they were single and because they were intimate, she was no longer eligible to be Queen."

And that was that. Camilla married Andrew Parker Bowles in 1973. Charles met Diana Spencer in 1980 and married her in 1981. But as has been documented, Charles never really got over Camilla and admitted to cheating on Diana while they were married. That clip is part of this documentary, as is footage of Charles and Diana speaking to the press after announcing their engagement and Diana's reaction when Charles said "whatever being in love means" after an interviewer asked about their love.

We won't spoil it. We'll just say it's something to look out for.

To be clear, "Charles: In His Own Words" is not all about the scandals of his love life. Jennings unearthed hours of never-before-seen footage of Charles as a young boy, at his investiture ceremony to become Prince of Wales and beyond.

"We went though and we found archives that hadn't been digitized before, stills that no one had ever seen before and I swear, every couple of minutes in this film, it's like wow I didn't know that," Jennings said.

We also see the beginnings of Charles as an activist, which started once he officially became Prince of Wales.

"The people of Wales were not very happy that Charles was going to be named Prince of Wales," Jennings said. "He doesn't run and hide. He goes up there and he meets with these riotous crowds and wins them over."

"And at age 19 that's where Charles got his passion for the environment and he still talks about it today, global warming and climate change."

The official coronation of His Majesty Charles III takes place May 6. Jennings says he believes his reign will change the monarchy. In fact, we're already seeing signs of that, starting with that coronation, where Queen Consort Camilla will officially become Queen, something that was originally forbidden.

"He plays a very long game with everything he does," Jennings said. "53 years later, he's married to Camilla, he's gonna be King and she's Queen."

Jennings also believes Charles will eventually repair his relationship with his son, Harry.

"He's been very quiet about what's been going on with Harry and Meghan. I think his arms are always open and I wouldn't be surprised in another 5 years if they have a fairly decent one," Jennings said.

"Charles: In His Own Words" airs April 28 on National Geographic, will stream the next day on Hulu. And it'll stream on Disney+ May 5.

The Walt Disney Company is the parent company of National Geographic, Hulu, Disney+ and this ABC station.