The Bachelor bachelorette was attempting to get back together with ex-husband Jason Vena, whom she had divorced about a year ago, ending their five-year marriage, just weeks before the show began to film, Life & Style reported in its February 7 issue.
"Right before she left to film the show, she told Jason she wouldn't go on The Bachelor if he took her back," a source told Life & Style.
O'Brien and Vena, who had been together a total of 10 years, reportedly divorced because she felt their relationship had lost its spark, but she regretted her decision to split from him soon after.
"She knew she'd made a mistake," the source said.
However, Vena was apparently over the bachelorette, as he was dating another woman named Tawny and refused O'Brien's "desperate" attempts to rekindle their relationship, according to Life & Style.
"Chantal begged and pleaded and cried. Jason was in a lot of pain over it, but at the end of the day he said no," the source explained.