Katy Perry has reportedly fallen for John Mayer and her friends are concerned that the relationship is doomed. According to RadarOnline.com, Katy is smitten with John and he wants to keep the relationship more casual. A source said, "Katy's friends and family haven't taken to John at all, in fact they are worried that she is headed for heartbreak. She's been telling everybody who cares to listen how great John is and it's clear that she is totally in love with him. At first, she was quite careful with John and said she wasn't ready for a relationship and just wanted to have fun. But now she appears to have fallen dangerously in love with him and her friends are concerned. Despite the fiery image Katy likes to present, she's actually more fragile than that, and when John dumped her a few weeks after they first got together she was devastated. Now that she has invested more feelings in John and has let her guard down, there's only one way this can end... in disaster!"