According to doctor Du Na, a doctor at the Fourth People's Hospital of Chengdu, Xiaoyu quickly became unnaturally obsessed with her boyfriend, wanting to know his whereabouts at all times and freaking out when he didn't immediately answer her texts. Sounds like your average control freak behavior. But according to the doctor, Xiaoyu suffered from a rare mental disorder called love brain. He was expected to reply to her messages immediately, doctor Du noted, adding that one day, Xiaoyu called her boyfriend more than a hundred times