It's Okay To Not Be Okay Spoiler: Is Gang Tae's mother's death linked to Moon Young's mom's disappearance?
It's Okay To Not Be Okay episode 10 hinted at the return of Ko Moon Young (Seo Ye Ji)'s mother. This has led us to wonder if her disappearance had a connection with Moon Gang Tae and Moon Sang Tae (played by Kim Soo Hyun and Oh Jung Se)'s mother's death.

Before we proceed, Mandatory Warning: Spoilers Ahead
The first half of It's Okay To Not Be Okay carefully layered in the mysterious death of Moon Gang Tae and Moon Sang Tae (played by Kim Soo Hyun and Oh Jung Se)'s mother. Although the details of the death have been kept under the wraps by the makers, it was revealed that the autistic Sang Tae was present when the mother passed away. On the other hand, the director has also weaved in the question about the disappearance of Ko Moon Young (Seo Ye Ji)'s mother.
Over the past few episodes, it was presumed that the mother - also an established writer - had died. Moon Young's father Ko Dae Hwan time and again murmured that the "monster" aka Moon Young's mother is dead and he killed her. He even announces it in the 10th episode when he realises that Moon Young's mother is actually alive. This leads us to wonder, who did Dae Hwan actually kill?
Given how intertwined Gang Tae and Moon Young's lives have been from their childhood, we've come down to a compelling theory: Could Dae Hwan have killed Moon siblings' mother instead of Moon Young's mother? What if it is her body in the basement that Moon Young sees as a child? With It's Okay To Not Be Okay episode 10 hinting that not only is the writer's mother alive, she has also decided to surprise her daughter on her birthday, but it does also appear that maybe, Dae Hwan killed Sang Tae and Gang Tae's mother.
Understanding Dae Hwan's intention to kill her, she took the opportunity of the death to disappear, leaving Dae Hwan to believe that she actually died. But what about the butterflies? While we try to wrap our heads around that, all the breadcrumbs laid by the director since the first episode hints that there could be a connection between Moon Young and Sang Tae.
We know it is a tad far-fetched. But what do you think of the theory? Let us know in the comments below.