The two characters here missed on that chance in the past and later ruined whatever they could have entirely. We meet them through the shaky, handheld camera which adds to the raw opening - Sumin prevents Sanghyeon from jumping over the roof into the presumed sea below the funeral home. The sea is a leitmotif here - its blending with the sky at the faraway horizon blends the morals in the story as well. And yet, after every wave, the sand is pristine again.
Sumin leads an uneventful life - she works as a nutritionist and her detachment from life is seen through the cafeteria scene in which she's the only thing that does not move. The buzz of the life around cannot penetrate her, so she even eats away from everyone. At home, she lives with her husband but she might as well be living alone - they lead separate lives and have separate bedrooms. He only cares to have food prepared and house run. In one scene he yelled at her that she did not go for groceries so he has no apples to eat. Because poor man has no hands, I bet. Their son studies abroad and does not want to spend any time with his parents, ignores calls from his Mother which makes Sumin feel even more alone and useless.
And then comes Sanghyeon, who just lost his wife and is raising their little daughter, moving back to Seoul because Jinwoo found him a job. And we learn that two of them were acquainted in the past. More - they were friends, and from the hints - maybe even more than friends even though it wasn't pursued. Worse - Sanghyeon set Jinwoo with Sumin because he said he liked her. And here we have the first instance of the cowardice that reared its ugly head 10+ years later. Probably that's why Sanghyeon left Seoul, even though it's not explicitly stated.
Sumin feels needed for the first time since a long time - she takes care of the little girl and both her and Sanghyeon start their ill-timed affair. And it soon changes into the titular crevasse - between themselves the most. Sumin is invested into the affair to the point she's ablaze with life and passion, even considering divorcing her husband. Which she ends up doing anyway, but not for Sanghyeon who rejects her, but for herself. At one point Jinwoo starts to suspect his wife has an affair and true to his nature, his possessiveness starts to emerge. He has no feelings for Sumin, but as he assures himself: she would never do this to him because they have a child together. To assert his "claim" to her, he tries to force himself upon Sumin, to her refusal stating that they're married and it's natural. Thankfully, she manages to leave.
Perinatal depression is generally recognized to be a common affliction among women during pregnancy and the first postpartum year. However, estimates of the prevalence and incidence of the condition vary widely—from 5 percent to more than 25 percent of pregnant women
and new mothers—depending on the assessment method, the timing of the assessment, and population characteristics. (1)
