You Deserve to Be Single (2010)

The film centres around three contemporary urban couples who are involved in what has been described as a romantic Infernal Affairs-Esquire chess game. A pair of brother and sister - Li Zheng & Li Ying one happened to be a love detective and the other a love expert, when affluent businessman Xiao Feng turns up, requesting the agency test the waters with his bride-to-be, pretty psychiatrist Fei. Li Ying is immediately overwhelmed, seeing Xiao Feng as a potential catch rather than a customer.