"I will love you forever … you're stuck with me," Robertson told Flajnik after he presented her with the spectacular Neil Lane engagement ring - and the final rose - while the pair stood in a clearing in the Swiss Alps.
The other finalist, fan favorite Lindzi Cox, seemed to take the disappointment well when Flajnik told her was in love with her but also was "in love with someone else."
"Good luck," the 27-year-old fan favorite, said, adding, "and if things don't work out, call me."
Appearing today on " Good Morning America," Cox said that line was meant to be a joke, uttered in a moment she described as an "awkward silence," not a sign that she wants Flajnik back.
"Hindsight's a really beautiful thing," the 27-year-old business development manager from Ocala, Fla., said on "GMA." "Looking back, it was tough for a little bit but he made his decision and did what's best for him and I wish him nothing but the best."
The woman who nabbed the ring over Cox was far from popular. Robertson gained a reputation for meanness when she trash-talked and antagonized the other 24 women vying for the California winemaker's hand. During her single-minded pursuit of Flajnik, she referred to contestant Nikki Sterling as "fatty" and called Blakely Shea a stripper.
In a previous episode, Kacie Bogoskie, who just missed being one of the two finalists, flew to Switzerland and warned Flajnik that he would have his heart broken if he chose Robertson, a 28-year-old model from Scottsdale, Ariz.
During the two-hour finale, Flajnik took Robertson and Cox on dates, and introduced them to his sister, Julia Flajnik, and mother, Barbara Flajnik. Both women had flown to Switzerland to give Flajnik support and advice.
Cox told Flajnik's mother that she would be honored to be the woman chosen.
"Your son is amazing. I've just completely fallen in love with him …," she said.
Flajnik's sister and mother liked Cox's warmth and sincerity, but expressed extreme reservations about Robertson.
"The girl that other girls don't like is typically a red flag. That doesn't sit well with me," Julia Flanik said.
But after they met with Robertson, they had a change of heart.
The model told Julia Flajnik that she initially tried to make a good impression on the other contestants, but when they weren't receptive, she stopped making and effort and just focused on Ben. Robertson also admitted she could have tried harder to reach out to the other women.
"She's a really amazing girl," Julia Flajnik said, speaking of Robertson. "I found her to be very, very sweet."
Flajnik's mother said she found Robertson "to be a very kind person … ."
Robertson may have won over Flajnik's mother and sisters, but she didn't make any friends among her fellow competitors.
In the Women Tell All special that aired March 5, Robertson was chastised by the other women for behavior during the show. Saying being on the show brought out the worst in her and acknowledging that she handled herself poorly, Robertson issued a tearful apology that no one seemed to accept.
Flajnik was one of the two finalists in the last season of "The Bachelorette." He famously had his marriage proposal rejected by Ashley Hebert, who accepted J.P. Rosenbaum's proposal.
He was clearly torn between both Robertson and Cox, saying several times that tonight that he had "fallen in love" with them.
Flajnik admitted having reservations about Cox because he felt she hadn't been vulnerable to him, and about Robertson because of the way she had been perceived by the other women on the show.
He said the choice would be hard, but added that he had never felt such a natural connection to a woman than he had with Robertson.
"She makes me feel like a little kid," he said, after spending a day with her picnicking on the mountainside.
In the "After the Final Rose" special following the finale, Flajnik revealed that he and Robertson had broken up for a time while the show was airing, but he confirmed that they were still a couple.
Flajnik apologized to Robertson for abandoning her when he should have been there to offer support, but said the distance was his way of coping with the negativity of the show - of seeing Robertson's behavior, and the other women's behavior in return.
He said it was "difficult to watch," adding that the situation was made even more challenging because they weren't able to see each other and talk about it.
A subdued Robertson admitted that she didn't fully trust Flajnik after not having his full support during the airing of the show, but said she still loved him and believed in him.
The pair sat close to each other and held hands.
Both teared up when they watch video of the proposal, Flajnik calling it "a beautiful moment" that had been "soiled" by negativity.
But when host Chris Harrison took the engagement ring out of his jacket and asked Flajnik what he wanted to do with it, he took it and put it on her finger.
"I very much want her to have this again," Flajnik said.
Asked whether he thought there would eventually be wedding, Flajnik replied: "Yeah, I do. When? Who knows?"