A teenage boy finds himself caught in the middle of a feud between his mother and his late father's gay lover in Dear Ex. Three months ago, Song Chengxi (Joseph Huang) lost his father Song Zhengyuan (Spark Chen) to cancer. Prior to his death, Zhengyuan came out as homosexual to his wife Liu Sanlian (Hsieh Ying-xuan) and left to live with his actor boyfriend Jay (Roy Chiu). This results in Liu having a deep hatred of Jay, especially since she believes he's the benefactory of Zhengyuan's insurance. This results in a bitter feud, with Song Chengxi stuck in the middle.
Dear Ex is a Taiwanese dramedy about a family coping with not only the patriarch's death, but the fact that he was a homosexual. The film is told primarily from the perspective of Song Chengxi, who is regularly talking about his feelings to a therapist. When Liu Sanlian hateful behavior becomes too much for him, Song Chengxi runs away and stays with his father's lover Jay and through flashbacks we learn of the connection Jay had with Song Zhengyuan.
It is obvious that Dear Ex is a film coming from a country that isn't fully accepting of homosexuality, as seen by how Liu Sanlian is almost cartoonishly homophobic, accusing Jay of stealing her husband and subsequently the insurance money. Speaking of cartoons, Dear Ex has a number of animated flourishes that illustrates the thoughts Song Chengxi is currently having. Ultimately Dear Ex is a film that is about learning to accept people how they are, no matter what their sexual orientation may be.