I'm glad they made some progress. I think 1 or 2 episodes will be like avoiding each other because he said stop being sex friends and after that they will confess. It's just my guess tho.
Also there is a chance that after he said “Let's stop being sex friends” get might confess. That would be short but clear.
I didn't get it. Why is he calling the other person Two Thousand??
It's an awkward translation of his name (which shouldn't have been translated at all since name are proper nouns). Korean names, like Chinese names, are words denoting concrete (eg. Sun, water) and abstract (eg. Love, courage) constructs, they may be paired together to create more profound meanings (correct me if I'm wrong). Like the Korean name "Haesoo" is literally translated as "sea water".
Okay so I'm gonna speak logically. We saw that teacher's future self doesn't remember meeting him. That means that every time he goes to past he's creating a alternative universe. That's how it works right? And we know that alternative universes are different. In this universe other guy is mean. That's what I'm thinking tho.
There is also a chance that he will have a break down in the future so his personality is going to change.
Aside from poor translation I think my parallel universe theory was right. Honestly I have no idea how he will go to the other universe.