Robertson and Luyendyk were reportedly photographed while they shared an intimate dinner at Quiessence, a restaurant in Phoenix, AZ.
"We're told they were all over each other the whole time," TMZ reported.
Robertson had tweeted a photo of a pair of wine glasses set on what appeared to be a romantic table for two complete with candles and flowers on Thursday night.
"Beautiful night... #RedWineImFine," she wrote.
Ironically, Quiessence was also reportedly the same restaurant Robertson took Flajnik to when he visited her in Scottsdale, AZ during her hometown date on The Bachelor.
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.
In their split announcement, Robertson and Flajnik -- who had maintained a long-distance relationship the last ten months -- stated they had "grown apart" due to "distance, time apart, and our need to focus on our respective careers."