Another world (reincarnated or transmigrated into another world, not set in a book or game)

She only BELIEVES that it's in a novel, but later finds out that it's just another world

Elise was originally born in the world the manhwa is set in, but dies somewhere before her thirties and is then reincarnated in the modern world, where she lives until her mid twenties, only to die once again and now gets reincarnated into her original body at the age of 16 (it's another world; not one from a game or book)

Smut

Reincarnation in another world, and then after dying there of old age, the FL and her loving husband were both reincarnated in the modern world