Abandon Me gently

The male and female protagonists deeply love each other, but due to misunderstandings, conspiracies, and obstacles from reality, they constantly miss each other and hurt each other. The female protagonist is deeply hurt and eventually leaves completely, unexpectedly passing away. The male protagonist doesn't understand his true feelings until he loses everything, and falls into eternal regret and longing. It's too late to save the relationship, and love becomes eternal regret, resulting in a heartbreaking ending.