"Our relationship has been tested pretty much the entire time we've been together," Robertson toldLife & Style in an interview published in the magazine's new issue.
"When I stayed [with Ben] for long periods of time, it helped. I think if we'd lived together, we wouldn't have broken up."
Robertson, a 28-year-old model from Santa Monica, CA, got engaged to Flajnik, a 29-year-old winemaker from Sonoma, CA, when he selected and proposed to her during The Bachelor's sixteenth-season final Rose Ceremony, which was filmed in November 2011 and aired in March.
However the couple -- who had maintained a long-distance relationship the last ten months -- announced their split earlier this month, stating that they had "grown apart" due to "distance, time apart, and our need to focus on our respective careers."
Earlier this week, Flajnik revealed the couple had decided to take a break after they spent the weekend in Sonoma together late last month but opted to "not drag this out" and permanently split a few days later.
"We weren't as similar as we thought," Flajnik told In Touch Weekly in a recent interview. "We really did love each other, [but] things just changed."
According to Robertson, the decision to split wasn't difficult.
"I knew I had no fight left," she told Life & Style, adding that she is still a believer in love.
"Right now I'm focusing on healing my heart. I'm a hopeless romantic and still believe I will find my soul mate. I need a guy who is ready for that chapter."