Fate's Invisible Thread by Nature Dash

The Red Thread of Fate connects souls destined to be together, no matter the trials of time or space. But for Phoenix, fate's lesson begins with betrayal. After taking the life of his fated partner, he is reborn on Earth-not as a man, but as an invisible guardian with the power to guide souls to their final destinations and witness the last moments of their lives.
Through his role as a watcher of death and the echoes of human lives, Phoenix's heart begins to change. When fate grants him a second chance through a time loop, he decides to rewrite his story-this time, to love her truly.