They caused a firestorm of stories when they were caught canoodling on a yacht in Italy over the July 4th weekend, but it appears things may have already cooled off between Michelle Rodriguez and Zac Efron.

Michelle Rodriguez & Zac Efron Kiss In Italy A Second Time?

Since returning to the U.S. following their nearly two-week break in Sardinia, the rumored couple haven't been spotted together even once, as Rodriguez has been spotted out twice without her new beau.

According to AM New York on July 14, the actress was spotted having a low-key dinner with a male friend who was not Efron at NYC's Beauty & Essex on July 12-and just three days later she was spotted arriving for a night out at Chateau Marmont in L.A.-also without Efron.

Michelle Rodriguez and Zac Efron A 'Good Influence' On One Another?

However, the lack of spending time together doesn't appear to be a sign that the relationship has already soured, as Rodriguez was all smiles as she arrived at the L.A. hotspot-giving new credence to rumors the two have been secretly hooking up for years-and have no interest in being an actual couple.

Hollywood Life reported in July 9 that the two have had a friends with benefits type of arrangement since 2011-not long after Efron broke up with his girlfriend of four years, Vanessa Hudgens in late 2010.

"Whenever they're together and both single, they hook up," a source told the website. "They're just having fun on vacation."

Even though the two have never been serious before, they did have more to bond over while in Italy, which made things a bit more romantic than they have been in the past.

"During The Rover after party, they hung out all night and really bonded with each other on a whole new level," the source added. "They both had something to bond over. He was there for her breakup and she was there for his substance issues and that bond has turned romantic."

Tags: Michelle Rodriguez Zac Efron