Beijing, summer 2013. Ambitious, 31-year-old Meng Yun (Han Geng) co-runs a small ad agency with his longtime friend from university days, Luo Qian (Wang Likun), and enjoys the typical yuppie lifestyle of a single man. Attending the wedding banquet of an ex-girlfriend, Li Xiaojie (Mao Junjie), he finds himself seated at a "former boyfriends' table" along with four other guys. Across the room is a "former girlfriends' table" at which a fifth member, hotel employee Xia Lu (Helen Yao), arrives at the last moment. The bride and groom publicly thank their exes for "contributing to our emotional growth". When the girls start brawling, Meng Yun escapes with Xia Lu and by the next day they're a couple. At a dinner at Luo Qian's flat one evening, Meng Yun becomes slightly jealous when she invites along a male friend, the older and more experienced Zhao Ming (Zhang Hanyu). Another evening, Xia Lu invites her best friend Xiaowen (Bai Jiajia) to meet Meng Yun's best friend and work colleague Yu Fei (Ryan Zheng), and the two hit it off. On the way to celebrating their first 100 days together, Xia Lu and Meng Yun bump into Xia Lu's ex, South Korean playboy Park Eun-ho (Lee Sang-yeop), and at the restaurant they bump into another of Meng Yun's exes, Shang Dan (Liu Yan). Xiaowen and Yu Fei separately urge them to come clean about their past love lives, though each professes to be uncurious. But Eun-ho continues to pop up in their lives, as well as some of Meng Yun's other exes, including party girl Mengmeng (Xiong Naijin). Their easy-going relationship starts to become strained.