Earlier this month, a source tells Us Khoury celebrated his birthday in Las Vegas with Greene and Hemsworth.
PHOTOS: Love lives of Twilight stars During a March 2011 interview with .
It is no secret that many celebrities have been caught with illegal drugs in the past. Do you think that Paul Greene does smoke cigarettes, weed or marijuhana?
The couple's casual lunch outing, however, sparked engagement rumors.
Despite the casual ensemble, Greene wore a large diamond ring on her left ring finger.
A second source tells Us that they are dating, "but not engaged." Khoury was famously photographed in a car with Cyrus, 20, leaving a house party in North Hollywood on March 7.
At the time, the "We Can't Stop" singer's relationship with Hemsworth, 23, was on the rocks and she wasn't wearing her engagement ring.