In the story "Lullaby" by Kim Chi-won, the cause of the death of the wife is deliberately ambiguous, with the possibilities including the effects of a supernatural force, suicide, or murder. Each of these possibilities is supportable in the story. The woman clearly has suicide on her mind in the period before her death and can be seen as having ample reason for wanting to escape from the life she leads with her insensitive and at times violent husband. He beats her on her last night alive--did he kill her and place her in the pond? The hints of a supernatural force could be imaginary or they could be real, though there is good reason to see them as real because the husband knows about the stories surrounding the house while the wife does not, yet she also hears the voices from the pond. Some combination of these possibilities is also possible--the wife may be attracted by the supernatural voices yet kill herself, leaving the husband at least morally guilty of murder for the way he treated her.
The fact that the woman has been seeking escape for some time is evident in her thoughts as she looks over the new house:
There were times, as when she slid open the door of their rented room and saw the sunlight slant into the garden, that she wanted to leave with he daughter, dressed just as they were, for some back-country place on Cheju Island or in the Ch'ungch'ong, or Cholla, or Kangwon regions. And sometimes she realized with a start that these thoughts of leaving the world behind, of going with her daughter to live beside a stream and watch the water flow by, were frightening (167-168).
She is frightened because of what she would be doing to her daughter, but there is also fear of the real meaning of these fantasies. That they are related to death is indicated by the repeated mention of water in the form of streams and rivers, while her death actually is caused by water when she drowns in the pond.
There is irony in ...