During a moment of national history when Barack Obama was officially sworn in, I can't think of any reason why Mariah Carey wouldn't be up there with him, possibly repeating everything he says through song. That would make perfect sense. At least that's what she seems to think according to Page Six:
A spy said, "Mariah was in the VIP area, where every celebrity, like Jon Bon Jovi, Mary J. Blige, Alicia Keys and Bruce Springsteen, was seated. But somehow she thought she'd be up with the Obama family. When she realized she wasn't, she bailed."
I think this is a case of Mariah falsely thinking all half black/half white people stick together. She probably thought the inauguration would end with her skipping into the sunset with Obama, Derek Jeter, and Alicia Keys. Wait, is Alicia Keys part white? I'll check into this.