John Mayer has apparently broken up with Katy Perry before their fledgling romance even really got off the ground.  Renowned as a ladies man, Mayer is said to have told the singer that he was a changed soul but running true to form, quickly became tired… they’re not said to have remained friends.  ‘John did a real number on Katy,’ a source told RadarOnline.com.  ‘She held off from his advances for the longest time, but he laid on the charm thick and promised her he was a changed man. She eventually gave in, fell head over heels for him and then – yep – once he had made his conquest, he dumped her.’ The website added that the couple were spotted at a friend’s dinner party on Tuesday night, where they completely ignore each other. ‘It was so weird! Katy stayed in one room the whole night and John stayed in the other and when they passed each other they both just kept their head’s down.  ‘It was like they had this incredible animosity for each other and everyone else at the party could feel it,’ an eyewitness told them. The pair stayed at the party late, regardless, with Katy chatting to a blonde model and John making small talk with a ‘busty brunette.’ Just recently he pair were seen here putting on a tactile display at a friend’s pool party in the Hollywood Hills. Katy, 27, cavorted around in a sexy two-piece – while John Mayer, 34, shot her admiring glances, seen in one shot with a huge grin as he wraps an arm around her.  One guest told Star magazine: ‘There was major chemistry between them… It was like they were on a honeymoon. Close friends of Firework singer Katy were said to be worried about her falling for the charms of badboy Mayer so shortly after her failed marriage to Russell Brand. RadarOnline.com