I FREAKING KNEW IT! He looked over sooo fast when he saw her stuck on the bridge after the concert, and he was…
I imagine a lot of his anxiety and depression was from not being able to save her. Maybe he even feels some guilt at her not being able to walk, that would make sense with why he never kept pursuing her after her accident if he had that big of a crush on her. So I get the feeling that if she can save herself it will save him. Either that, or he didn't commit suicide. That knock on the door was really suspicious.
So something that I thought was very off about these last three episodes were the fact that every time Tae Sang gets injured, it seems he heals very quickly where as in the first part he stumbled around for 7 episodes from the initial stab wound. But since episode 8, one minute he would be mortally wounded, and then the next day he would be fine. This started after he escaped the hospital with the help of Maeda. He was all beat up, stab/bullet wounds, scratches all over his face. Then he wakes up, we learn, four days later in Maeda's house, not a scratch on his face. and until he gets injured again, he seems to be doing ok considering how badly he was injured. What if he had the scar since being at Maeda's? Like maybe she did something to him that made him heal faster. Maybe she did it to herself too and that's why she survived the blast. Like she still scarred, but maybe she healed fast enough to survive the explosion. Maybe she had the means to do this via her funding the hospital's research. Just a theory, but it would explain a lot, including how he was still alive at the end without it necessarily being a najin.
I have been waiting all season for Naksu to regain her memories so she can kick some butt with Uk. It had better happen! I kind of thought that was the point of giving her her body back...but whatever.