The title of the book is the name of a song, which is awesome.
The heroine wants to die every day, but she is reluctant to die every day.
So the system called Saving Humanity took a fancy to the tenacious strength of the heroine and asked her to save her own marriage...
A messy synopsis.
To put it simply, the heroine travels through different time and space to save the male protagonist who wants to die in various time and space, and ends up dying in various ways...