Orlando Bloom is romancing Jennifer Aniston while still dating Aussie model Miranda Kerr, NW reports

"Orlando is so busted," a pal says. "He thought he could cheat on his girlfriend and not get caught — with Jen of all people. But the news made its way back to Miranda in no time. What was he thinking?"

Insiders say Orlando, 31, and Jennifer, 39, were flirting at a recent charity bash.

"Jen started following him around, jealously making sure no other woman grabbed too much of his attention," an onlooker says. "Once Orlando worked out what was going on he started to ferociously hit on Jen. Their chemistry was undeniable."

"They got very touchy-feely and they didn't care at all who saw them," a source reports.