I used to think that Eun-joo was a crazy homewrecker who wanted to abuse the girls as much as possible but after watching this movie for a third time, I felt like the status of Eun-joo being the villain was quite exaggerated. It wasn't Eun-joo who allowed Su-yeon to die. Su-yeon died because Su-mi distracted Eun-joo from expressing her hatred towards her and its even worse when Eun-joo even planned to HELP Su-yeon despite her obvious rift with her stepdaughters. Despite her obvious flaws, Eun-joo had the patience to deal with problems better than Su-mi who continues to unreasonably lash out with violence and hold a grudge against her even after she attempts to reconcile with her.
"I used to think that Eun-joo was a crazy homewrecker who wanted to abuse the girls as much as possible but after watching this movie for a third time, I felt like the status of Eun-joo being the villain was quite exaggerated. It wasn't Eun-joo who allowed Su-yeon to die. Su-yeon died because Su-mi distracted Eun-joo from expressing her hatred towards her and its even worse when Eun-joo even planned to HELP Su-yeon despite her obvious rift with her stepdaughters" - edwintrinh09
I agree. It seems that many people believe that Eun-Joo knew, beyond a shadow of a doubt, that Su-Yeon would die if she left her under the wardrobe while dealing with Su-Mi's attack. It's almost as if people think that Eun-Joo can see exactly what we see when the camera shows us Su-Yeon in the wardrobe, she cannot. Eun-Joo was freaked out by what she saw in the bedroom and started to leave, maybe to get help, we don't know. What we do know is that Eun-Joo thought better of it and turned to help Su-Yeon directly, but was delayed by Su-Mi.
Yeah Su-mi was the reason why Su-yeon died even though the movie makes it seem as if Eun-joo was the one who killed Su-yeon. I'm wondering why Eun-joo is the only female character who doesn't appear to be mentally unstable in any way despite the fact that she was the one who could have potentially helped Su-yeon but didn't.