Then she told Forester she actually had gone to Aruba on a surprise family trip.
In fact, the 35-year-old beautiful, blond Maryland woman with a radiant smile had traveled to the Caribbean with a man named Gary Giordano, a 50-year-old businessman also from Maryland with a disturbing past.
Now, Gardner is missing and presumed dead, Giordano is being detained, and questions are mounting about what happened during their island stay.
Graphic PhotosThe mystery has only deepened as authorities in Aruba begin releasing details from the investigation.
The most recent shocker was the discovery of graphic photographs on Giordano's digital camera. The images, a source tells PEOPLE are "beyond pornographic."
No other information about the photos has been revealed, and it's still not known exactly when the pictures were taken.
It's the latest surprise in a case that had already gained notoriety because of its parallels to the unsolved disappearance of Natalee Holloway, 18, from Aruba in 2005. The suspect in that case, Joran van der Sloot, is being tried this fall in Peru for the murder of another woman. The Natalee Holloway Resource Center has opened a tip line for the Gardner case.
The leads have been provocative. Along with the photos, authorities revealed they're looking into a $1.5 million accidental death insurance policy that Giordano reportedly took out on Gardner before their trip.
Pedro Famous Diaz / AP
Arrived TogetherSo how did Gardner end up with him?
Gardner's roommate and friend Christina Jones says the two met online about a year ago and had been platonic friends, speaking occasionally. He had asked to travel with her before, but she turned him down.
Then, in late June, when Gardener lost her job as a patient coordinator in a dental office, she accepted his offer for a free trip to Aruba, then told her boyfriend she was off with her family.
"She went on the trip because she trusted him," Jones says, "to clear her head after losing her job."
Jones and Gardner's boyfriend both refuse to believe Gardner would have sex with Giordano or pose for the photos.
"This wasn't a part of our life. Ever," says Forester. "We already know he has a long history of this sort of behavior with women. Robyn would never consent to this."
Witnesses say Gardner and Giordano arrived together on July 31. Two days later, Giordano called 911 to report that Gardner had disappeared. He told police that she had never returned from an evening snorkeling trip they took on Aug. 2.
On the day of her disappearance, Gardner reportedly sent Forester, 40, a message on Facebook that read: "Don't worry. I care about you, I love you, we'll talk and sort things out when I [get] back. "
For now, as investigators continue to sort out how and why Gardner and Giordano were together, Forester is expressing doubts about Giordano's story, including the account of snorkeling. "She wouldn't go in the water above the waist because she wouldn't want to mess up her hair," he says.
Giordano was arrested on Aug. 5 at the airport where he allegedly changed his original flight to an earlier one. He had agreed to stay to help the authorities but decided to leave the day after Gardner's mother arrived.
Additional reporting by SIOBHAN MORRISSEY