Memories Off (2001)

Tomoya Mikami's life changed one day when his girlfriend Ayaka was hit by a car and killed on her way to meet Tomoya. He blamed himself for her death and never was the same after the accident. He began acting callously towards Yue and his other friends. Furthermore, every time Tomoya gets involved with a new girl, he sees images of Ayaka in his dreams. He decides he needs to find a way to say goodbye to his lost love once and for all, while dealing with several side romances at the same time. (Source: ANN)