" There have been unconfirmed rumors that Pattinson and co-star Kristen Stewart are dating.

If there's any truth to these allegations, the actress won't be happy to hear that her man and Dutra were reported to have "serious chemistry and looked like they were having an amazing time" at the Cannes event.

"It's sad for him because he's ready to admit his love to the world, and she's not," one insider said at the time.

VIDEO: Kristen and Rob in happier times Indeed, it wasn't until October 2011 that the actress, 22, finally confirmed their relationship -- by accident.

Speaking to a British shooting, she hoped to explore the country more "because my boyfriend is English." (When the reporter called her out on her admission, Stewart's teasing reply was, "I never would have said that if I knew you were interviewing me," before adding, "Come on guys, it's so obvious!

Despite their recent appearances out in public together, Robert Pattinson is said to still be very much struggling to move past his girlfriend Kristen Stewart's much-publicized affair this summer, and according to new reports, with VERY good reason!

Because although she was only caught with director Rupert Sanders, sources close to the actress reveal that she has a such LONG history of infedelity that friends of the pair are surprised it took R-Patz this long to catch on…and her track record includes stepping out on the “When they first got together, she was going back and forth between Rob and her ex-boyfriend Michael Angarano.

Eventually she did end it completely with Michael, but it went on or a lot longer than Rob ever knew. And obviously, she has SERIOUS problems with fidelity, and we doubt even the public humiliation of being caught in the act would deter her from falling into old habits and taking advantage of her man's trust!Everyone knows about their [Kristen and Taylor Lautner's] friendship, but not very many people know how close they really got. Again, it WOULD help explain - or at least reinforce - Rob's difficulty moving past the recent, ahem, 'incident!' We just hope that he can figure this whole mess out with no more pain and heartbreak than he's already endured!And have the strength to do what's best for HIM, even if it's harder than the alternative!"Erika was introduced to Robert by a mutual friend at the beginning of the night and he was smitten with her from that point on," a witness said."He took pictures of her, sat with her all night, and the two of them were even seen kissing!