Answer:
The most likley reason that the poet wrote these lines is that something has died. And so the poet is speaking about sadnes and lonelyness. The Belle Dame has gone away, she is beautiful and gone.
La Belle Dame sans Merci maybe the reference to death, as a dame with no Merci as death can be. An so no birds sang, this means sadness, or another reference to death. The sedge is wither'd from the lake, means something died.
Explanation:
The reference to the sedge is wither'd from the lake: this means death. The squirrel's is full, and the haverst's done, means there is nothing left to pick up, it marks and end.
This is a story of a knit-at-arms, which was in love and then the Dame dissapeared. The image of death as the end of something, it can refer to the lost love and also it may refer to the death of the knight.
