The Faioli is a race of fairylike
beings with wings of light
and with distinctively feminine
attributes, which inhabit the interstellar space
. ("Inhabit" is the best applicable term, since they are in many ways unlike ordinary living beings
They are drawn to life, and cannot sense death in any way; this includes inanimate things, even if they're mobile, like machines. It is said they feel when a man's death is near, and they come to take his soul when his time comes. But before she takes his soul, the Faioli gives the dying man a month of unimaginable bliss -- indeed, she loves him to death.
A Faioli travels from place to place upon the astral winds, flickering into existence when they find a place to stay for a while, and a man that needs their ministrations. She then assumes the form of a young girl and approaches the dying individual, to be with him until the end. When the period is up, the spark of life being nearly extinguished, the man yearns for the kiss of death which she bestows.
The Man Who Loved the Faioli is a wonderful short story by Roger Zelazny which tells of such an experience.