This is a kdrama I recently remembered about! It came out of nowhere and I can't find it, I really want to watch it. I think I only watched an episode this is what I remember-
I think in the cover or the intro there was a man and a girl in 2 separate rooms, and I think a red line was cutting straight through their rooms.  and then I think the man grabbed some coffee and went to his job- I'm not sure but I think he was a middle-aged man. and basically, the girl and the man are living in two different times. I don't remember if it was the guy or the girl who was living in modern time, but it might have been the girl. and they also had like a staircase like it was an apartment. So, the girl would come home in the evening I think, and the guy would come at night and leave in the morning. basically, they live in two different times but also right next to each other as neighbours.
Keywords-
two people living in different time units
It's/was in Netflix (I think)
a man and a girl
they are neighbours

someone please help me figure it out!
and I think they live alone too!