Responses
Yes. I'm sympathetic to both sides. Technically they aren't in a romantic relationship but *emotionally* they are both entangled with each other, attached to each other, and respond accordingly. Gyeo-wol is not interested in Winter only as a friendly senior and they both sense the truth of that on a certain level.
I think why MC still wanted explaination was because ML knew MC's feelings. He rejected saying that all it was because of work and career first. Now MC sees that dating rumors. Now maybe he thinks ML lied. Getting no explaination from his side since he said career and work first, so maybe it meant he was lying instead of telling the truth since he knows MC's feelings.
So it's like: You knew I liked you. I didn't get a simple explaination about that rumor and you told me work and career first but now I see you dating someone else. Is this the way to make me crush my feelings for you? Don't you know how this hurts me? There wasn't even a denial about the rumors. You could've told me you liked someone else and not this bs... Now I hear your cold explaination despite knowing my feelings, did you even consider me?
Well whether you agree or disagree, an emotional person can be irrational logically. Winter is also still young and new in love.