I don't know but to me this looked like rebound sex. Yoon definitely felt uncomfortable and insecure seeing that painting of Inhun but, Na-kyum sort of confessed that he has feelings for Yoon; even though Na-kyum himself is yet to realize it. He needs to tell Yoon the hurtful things Inhun said to him so they can finally get rid of his bitch ass.
I don't know but to me this looked like rebound sex. Yoon definitely felt uncomfortable and insecure seeing that painting of Inhun but, Na-kyum sort of confessed that he has feelings for Yoon; even though Na-kyum himself is yet to realize it. He needs to tell Yoon the hurtful things Inhun said to him so they can finally get rid of his bitch ass.