Jennifer Aniston and John Mayer have called off their relationship—again. The 31-year-old singer "needed time to himself," Us Weekly reports. The split leaves Aniston alone on her 40th birthday next month. "She's a control freak, and he can be very incommunicative," a source said. "Plus, she feels he plays games with her head." Like the last time they broke up in August, it might not be The End. "They have different needs, and it's hard making it work," said another source.