The mag has lead with a cover splash claiming to have photographic evidence of the supposed secret snogfest, and alleges that they were spotted together just last week.
HOWEVER, an 'insider' has told People.com that "Kristen wasn't having an affair with Rupert," and that the moments of steamy canoodling were "a mistake and a complete lapse in judgement," claiming that "Kristen is absolutely devastated.
"It was just a fleeting moment that shouldn't have happened. She never meant to hurt anyone. She's a good person who just made a bad choice."
Rupert - pictured above with Kristen - has two children and is married to Liberty Ross, who has since allegedly claimed that the pictures Us Weekly has printed are in fact of her and Rupert, not Kristen.
They have since taken the article down from their website.
Being big fans of Robsten, we're hoping that the claims are all false and that they're still happily biting their lips and being all intense together, staring into each others' eyes and listening to 'deep' music, especially since Rob recently told Italian Vanity Fair that he doesn't believe in cheating;
"There is one thing I've never understood: Why people cheat," said Rob.
"My parents met when my mom was 17 and my father 25, they are still together, and seem very happy. I grew up believing that you can be together all of your life."
OH GOD HERE COME THE FRICKIN' WATERWORKS.
PICS: US WEEKLY / PA