it was heavily implied that hyeon's constant worry over yiseon's well-being equates to his feelings for yiseon. hyeon questioning his decisions every time he saves yiseon were also signs that he was falling in love instead of keeping him as a member of his team. he realized all of this by the time he saw yiseon jumping
So basically he (Hyeon) was ignorant about his feelings.
he wasn't aware tbh because the way he thinks is more complex than how normal people think. for example, he justifies everything as a part of his plan but in reality, he was bending his plans just so he can keep saving yiseon.
hyeon does not seem to know what love actually means until the suicide triggered him
It's just ended like that. All is well in the end, that's what matters, I guess. I hope that there are extras.
But I have a question that I want to ask you guys. I can see how Yiseon fell in love with Hyeon, but when did Hyeon fall in love with Yiseon?? He always treated Yiseon as an important object or property that he couldn't lose. Or is it the pity for Yiseon that changed into love??