Both MinWoo and SeoJun are red flags, or at the very least, not suitable for JooHyun. Now, before you come flaming at me.. there's a lot with this.
Yes, SeoJun is an ass. This isn't the first time he's done it without a condom and he knows the consequences; same guy who was worried as hell that he gave JooHyun a contraceptive pill and disguised it as a painkiller. Not to mention the fact that JooHyun was in his heat—making the stakes higher. And he goes and does it again, and does not in fact, pull out. He's forced himself on JooHyun—let's also not forget that. I'm guessing the author tried spinning the narrative that SeoJun had suffered trauma, or that's what it seems to be. But that doesn't make him likeable; and I don't think people are buying that narrative; as they shouldn't. What SeoJun should do, or at least should've, is legit healed from that. He definitely still has remnants of PTSD and for many individuals, it plays out in different ways. The saying, "victims create more victims" plays so well into it without it being the intention. Trauma doesn't automatically make you a better person. Let me put it this way; a victim of abuse might say they won't ever become an abuser, but once they end up in a relationship, they could do just that. This doesn't apply to all individuals victims to abuse, but some victims of it end up becoming an abuser because of the trauma. It doesn't necessarily have to be the same type of abuse they suffered—it could be a different type. And it's not abuse (to them) because it's not the abuse THEY suffered. It's simply what's playing out between SeoJun and JooHyun.
But I won't fall for the MinWoo propaganda. You guys are under spells and need to snap out of it. Yes, he was a biiiit more leverage since he's known JooHyun since childhood. But guys...JooHyun is in college and an adult. I don't care if MinWoo is looking out for JooHyun—at the end of the day, it's up to JooHyun to decide who he hangs out with, who he fucks, who's baby he'll carry; I can go on.