Some people get mad over Minjae's reaction. I personally think that's normal. Of course you gonna be happy if you were confessed to especially by someone you look up to or idolize.
Minjae clearly respects his teacher greatly and thinks highly of him and I don't think he will cheat on Woochan, instead the hesitation (he doesn't know what to do) is because that guy is his teacher and of course don't you need to consider about the other party feelings too especially when you need to reject them without hurting the people that you cared about.
But still I hope they return back to their own body soon. This is getting risky (I think the teacher may have started to like the Woochan-who-is-actually-Minjae)
TOP MEGUMI SUPREMACY. Thank you for the food, I've been starving long enough for the semegumi's content in this fandom