Roger Neal revealed why the late TV personality's longtime love turned him down.
"Bob actually asked Nancy to marry him several times, she said no," Neal tells ET. "She was fine with the way things were. She loved being his companion, but he did want to marry her."
Barker was married to Dorothy Jo Gideon from 1945 until her death in 1981.
"I think, if you're lucky, you find your soulmate and the love of your life," Neal tells ET in an interview. "I think once you find that person some people don't want to replace that. I just always felt with him that he had such love and respect for her."
Barker went on to meet Burnet at an animal rights event, and the pair was together until his Aug. 26 death at age 99.
"They never lived together. They had separate residences," Neal says. "I think if he ever contemplated marriage again it would’ve been with Nancy for sure."
Neal adds that Barker and Burnet had "great admiration and respect for each other" during their 40-year relationship.
"I know he loved her," he says. "I know that she cared deeply for him."
Over the years, it was Burnet who took "amazing care" of Barker, who died in his sleep at his Los Angeles home.
"I can't stress enough the great care that Nancy took of him. It was around the clock," Neal says. "The fact that he got to stay in his home -- the same house since the 1950s -- to be able to live there his whole adult life and be able to be at home when he passed, I think it was very fortunate."
"The last five years of his life she was completely devoted to making sure that his healthcare, that his care on a daily, around-the-clock basis, was the top," he adds. "In my opinion, she is a saint for having done that. I don't think anybody could have done the job she's done. I think she was the absolute best person to take care of him."
As for Neal's relationship with Barker, that began decades ago, long after the publicist became a fan of the late TV host.
"I started watching him as a kid on Truth or Consequences, and then as a teenager on The Price Is Right," Neal recalls, "and then I came to Hollywood to start my career and I ended up representing him at 25 years of age."
Neal last spoke to Barker last December, at which time his client was in good spirits with his humor firmly intact.
"The nurses all doted on him. They just loved Mr. Barker," he says. "I said to the nurses before I left, 'You're taking care of the world's greatest MC. He is a legend.' And he said, 'I'll agree to that,' and started laughing. It was great."
Neal's final sighting of Barker came just weeks before his death. While Barker was asleep during that visit, his publicist notes, "He looked terrific, as terrific as you could look to be 99 and almost 100."
Now that Barker's gone, Neal says he'll "just miss knowing he's there."
"I would just call him up every once in a while and say hello and I can't do that anymore, but I'm thankful for the time that I had working with him. I'm thankful for the friendship," he says. "... There's a lot of memories... He's been there our whole lives."
Neal's not the only one who will miss Barker; tributes were quick to pour in for the late TV personality in the wake of his death.
"I was very happy to see the outpouring of love for him. I'm so happy for him. He knew that he was loved. I'm just not sure if he knew he was loved this much, which is so heartwarming," Neal says. "I'm so thankful because he deserves it. He was just an amazing person... He was a very generous man. What you saw on TV is what you saw in real life. He's irreplaceable."
Neal knows Barker's fans are likewise mourning his death, telling ET, "Not everyone can handle that kind of fame, but he had a love affair with the audience and they had a love affair back with him. He truly loved his fans, his public, and I think they truly loved him... He's a very rare person."
As for how Barker will be remembered, Neal says, "He lived a wonderful life and he helped mankind and animal kind and he left this planet a much better place than he found it."
"I think he leaves a legacy from television that will not be matched, will not be duplicated. I think he leaves a legacy for the animals. I think if animals could talk they would all be applauding Bob Barker today," Neal tells ET. "... I think he's one of those people that took that platform that he had, the celebrity that he had, and used it for absolute good to make the world a better place. I think the world is a much better place having had Bob Barker in it."