Do you think Killing Stalking is a Stokholm Syndrome Story

Yes, it is.
Yoon has BPD, Borderline Personality Disorder, and so he's a bit...different.
Borderline personality disorder (BPD) is a serious mental illness that centers on the inability to manage emotions effectively. The disorder occurs in the context of relationships: sometimes all relationships are affected, sometimes only one. It usually begins during adolescence or early adulthood.
To be in pag-ibig with someone who abuses you and even threatens to kill you is probably a clear sign of Stockholm's Syndrome. Seeing as most people would just grow to resent someone...