
He likes Seonjae as a friend and a person, he actually likes all the brothers but his like for Juwon is clearly different, you can tell by his expressions
(Spoilers)
Juwon is the endgame obviously XD Those two dorks are obviously inlove but too oblivious or shy to each other XD but Miho helps them(I thought of Miho as the bridge of their relationship lmao)

He obviously meant as a friend and because of that he said he have to tell the truth to him but Seonjae took him to a loud place so he wouldn't hear those words and settle things. Btw Since he's a vampire he's ears are sensitive so his ears would bleed because the place is so loud. He really need to face reality either way because Dongha do have feelings for Juwon
Did he just say he LIKES SEONJAE??? NOT JUWOON?? HELLOOO, no.