Mao’s father, who remarries and brings Shiori into the family. Viewer Reception Heartful Maman the Animation (Video 2017) - IMDb

However, based on the specific phrasing , the most accurate match is the emotionally devastating and beautiful short film from WIT Studio:

: The story follows Mao Kinosaki, a college student whose mother passed away years prior and whose father abruptly left him after he entered university. The narrative centers on Mao's emotional struggles and the manifestation of suppressed feelings following his mother's death. Production