As PEOPLE reports in its latest issue, Witherspoon, 31, and Gyllenhaal, 26, checked into the Carneros Inn in the Napa Valley last Sunday, and went on to spend a cozy 24-hours in one of the resort's private homes.
"They were very affectionate with one another," says an onlooker. "They were cuddling, and he kept giving her little kisses."
The two even bailed on a couples massage in favor of an evening in, the source says, adding, "It was clear they wanted to be left alone."
It Started in SpringAlthough initially careful to avoid the spotlight when they first began dating, Witherspoon and Gyllenhaal's relationship first got noticed when they were spotted March 23 dining with two other couples at Los Angeles's Il Sole – where they were "being playful," an observer said at the time.
Although the pair didn't have much screen time together while filming Rendition for eight weeks in Morocco, during a reshoot in L.A., "Jake went and reintroduced himself to Reese," a source close to both actors told PEOPLE.
From there, said a friend of Witherspoon's, "Things slowly progressed, but it was never something she thought would happen from the start. She just kind of developed this little crush over time."
Only by June, that crush had been crushed: "They just recently broke up," a source in Witherspoon's circle told PEOPLE. "It's totally and completely over."
Except, little by little, the pieces started coming together again.
"Jake's cute," Ellen DeGeneres told Witherspoon on the former's TV show last month (while Witherspoon was promoting Rendition). The Walk the Line Oscar-winner swiftly concurred.
"Yeah," Witherspoon replied with a giggle. "He's great."