Responses
I think it's kind of stated that they have this unexplainable pull towards each other. Seunghyun tried to talk himself out of it by saying it was just work. Heesu kwas also warned against the feeling by his sunbae. But you can't help how you feel I guess.
I think it's more of a psychological complex than a fall in love, especially since he sympathizes with him and at the same time he saved him.
Aren't they "falling in love" quite fast? Or maybe that's just me, I could never do that in 24hrs