In the short story, "The Demon Lover," by Elizabeth Bowen, Kathleen, the protagonist, finds herself questioning the promise her fiancee made twenty-five years earlier. The promise is that "I shall be with you . . . sooner or later. You won’t forget that. You need do nothing but wait.”
However, in the interim, Kathleen has married and has a family who lives in the country. She has returned to the London house to pick up some belongings when she finds a mysterious letter presumably from her fiancee who had died in the first war. The eerie letter suggests that she will meet her fiancee, K., at the appointed time on the date of their anniversary. This is the same date she has appeared at the empty London house.
The ending of the story suggests that somehow her dead fiancee has returned, and he drives Kathleen away, screaming, in the taxi. It appears he has fulfilled the promise to be with her "sooner or later."