
Sure it have STARTED consensually but it didn't end that way. Yeon begged him to pull out and stop because it hurt so bad when they did it the first time. Hell he even pushed him away and tried to ESCAPE, which is a very clear retraction of consent. Seo-in didn't want to stop, dragged him back, and kept having sex despite Yeon's objections. Clearly RAPE.
Sure the second time they had sex wasn't as violent but even then it's dubious at best. Yeon always expresses discomfort, asks to slow down and such but Seo-in never listens. The only time we see Yeon actively consent and engage in the sex is in towards the end when he wraps his legs around Seo-in and clings to him in chapter 30 or 31.
I seriously can’t with people who see bigger problem with Taegu who never acted (as far as we know) improperly towards Yeongwoon, didn’t even hit on him as far as we know now when MC is a whole ass adult in his mid 20s than with Seo-In who is classified harmful rapist.
And don’t even start with trauma excuse