Mariah Carey's friends think her boyfriend, Bryan Tanaka, is ruining her life, at least in the professional world. According to a new report by the New York Post, Mariah's boyfriend has taken control of her day-to-day operations even since she split with her longtime manager, Stella Bulochnikov. "Bryan is behind the whole split between Mariah and Stella. Bryan believes that he should be the one running Mariah's day-to-day life, and he's been orchestrating Stella's exit for a long time. No one enjoys working with Stella. There's no secret that some people are happy she's out of the picture," a source told the Post. But, "the boyfriend backup dancer definitely isn't the right person to run her career." Her friends are predicting a career disaster. "This is a full-on Britney-and-Kevin Federline situation," a separate source said. "Brian is a backup dancer, and knows nothing about managing an iconic artist."