After I Sacrificed Myself for the Dao, the Immortal Lord Sacrificed Himself for Love

Watching Her Die Before My Eyes at the Moment I Loved Her Most, Helpless to Save Her

Ideally a short story. There are many ways to die young, not just from a serious illness but also from being murdered and so on. In many novels, there's always a last-minute twist when a crisis hits, but real life isn't like that.