Lin Yutang's collection Famous Chinese Short Stories contains a story by Yuan Zhen that is not simply a translation but a retelling. Lin Yutang follows Yuan Zhen's story until a certain point and then uses some of the author's poems to fill in gaps.
At a certain point in the story, the male protagonist, Yuan, sends a love poem to Inging (or Yingying in pinyin) and later receives one back:
That evening, Rose brought back a poem by Inging, which was entitled, "Full Moon Night":
Some one waits in the moonlit night
In the western room, with the door ajar
Across the wall, the flower shadows move —
Ah, perhaps my love has come!
That was February the fourteenth. Yuan was overjoyed.
I assume Lin Yutang wrote "February the fourteenth" because people in the West know this date as Valentine's Day. However, Valentine's Day wasn't something the Chinese celebrated during the Tang dynasty (618 to 907 A.D.), when the story was written. So my question is what "date" or festival day (if any) Yuan Zhen used in his short story.