What is the main conflict in the novel, What We Were Promised?

When Wei receives an unexpected call from his estranged brother, Qiang, his brother informs him that he intends to visit them to see the World Expo. Wei, who is crumbling under the shame of not pursuing a more noble career and feels emotionally distant from his wife and daughter, is nervous to see his brother again after 22 years. And Lina, who is suffering from the loneliness and aimlessness of her life in Shanghai, is uneasy because all the feelings she had once harbored for her husband’s brother have resurfaced because of his impending visit.