I agree, I don't know why but there is always something off. Besides my gaydar is going off like crazy with him, I don't know why he seems to have almost no on-screen chemistry with most of his female leads. Unlike Lee Jun Ki (where my gaydar has been going off since he started JG Style, for his fans) who has on-screen chemistry with his female leads in SPADES, JIW just ... either he overhams or his character pines away and you are not buying it because it doesn't work even though he is a good actor and his dying scene in TMTETS .. I was crying because with a different script his character could have shone very well.
I have started Flower Boy Ramen Shop and he has more bromance going on in the short scenes with Jae RIm (who played Woon in TMTETS) than with his supposed OTP.