Mesnick, a 32-year-old single dad from Seattle, proposed to Melissa Rycroft in New Zealand. But in the subsequent "After the Final Rose" special, taped six weeks later, he dumped Rycroft because he still had feelings for runner-up Molly Malaney, after weeks of no contact. He and Malaney are now dating.
Fleiss said producers have "zero" influence in selecting the woman who wins the final rose.
"The great thing about unscripted television is that it's unpredictable, and that's what this was," he said of Mesnick's decision to let Rycroft go and rekindle his romance with Malaney. "It caught us off guard. It caught the viewers off guard."
Mesnick has been the target of passionate discussion on Internet message boards and forums for rejecting Rycroft in such an alarmingly public format. An angry torrent of viewers, including Elisabeth Hasselbeck and Trista Rehn, lashed out at Mesnick, throwing verbal stones and questioning his moral character. They overwhelmingly supported Rycroft, a 25-year-old sales rep from Dallas, who'd fallen in love with Mesnick and planned to be step mother to his 3-year-old son, Ty, from a previous marriage.
She bristled with anger as she cursed at Mesnick, gave him back his ring, told him never to call her again and walked off the stage. He then asked Malaney, a 24-year-old department store buyer from Grand Rapids, Mich., for another chance and she agreed.
Mesnick defended his actions in a post-finale appearance on Jimmy Kimmel's talk show, saying his relationship with Rycroft went sour when the cameras stopped rolling and she "knew exactly what was going on" before her rejection at the "After the Final Rose" taping.
"It just wasn't working out for them," Fleiss said. "She knew it. She didn't know that it was about Molly - I think that was the thing that caught her off guard."
Mesnick said he had to break up with Rycroft on camera because of his contract with the show.
"There was no contractual obligation," Fleiss countered. "You can check the contract. ... How would you put that in a contact anyway? Like, everything you do in your life must be shown on ABC. It's impossible."
The Associated Press was unable to immediately obtain a copy of the "Bachelor" contract that contestants must sign when they agree to appear on the show. ABC representative Cathy Rehl directed a request to Warner Horizon Television, an arm of Warner Bros. Television, which produces the show. Warner representative Natalia Desrosiers said she was not authorized to provide a contract to the AP.
Either way, Fleiss televised the drama.
"It's a TV show, and that was really the defining moment of this series, and to not put that on TV seems strange, really, when you consider that we are making a TV show and these people signed up to do a TV show," Fleiss said.
Mesnick and Malaney pulled out of Wednesday's teleconference with Fleiss because ABC said both had scheduling conflicts. They could not immediately be reached for comment.
The second half of "After the Final Rose" aired Tuesday night. Mesnick and Malaney appeared in happy-couple mode, and host Chris Harrison announced that castoff and fan favorite Jillian Harris will be the next heartbreaker on "The Bachelorette," slated to premiere in May.
Fleiss said he initially tried to woo Malaney to be the "Bachelorette" - until Mesnick revealed his change of heart. He said he tried to get Rycroft on board but she was not interested.
"I would venture to say that she's probably the most popular girl in the country right now," he said. "I hope some of that is a positive for her."
Rycroft, who isn't talking to the media, said in a statement provided by ABC that she has no regrets about her reality TV experience but wants to move on "and get some sense of normalcy back" home in Dallas.
"I'm in such a good place in my life right now, and I really couldn't be happier," she said. "I don't regret anything that happened over the past few months, because I know I wouldn't be where I am today had none of it happened."