This chapter confirm something that I have wondered for quite a time now. Woojin DOES have sort of obsession/liking towards Wooyeon. Look at the subtle expression of his when Wooyeon initiates something to him (convo and hand holding in this chap). Woojin wants ALL of his hyung's attention and only to him, no one else's. This may be stemmed from their childhood which gradually snowballed into what happened in the present.