What webtoon am I thinking of?

I haven’t been on Webtoon in a while but I distinctly remember one that I really loved but cannot remember the name. It essentially is about a girl who lives in an apartment and things sometimes don’t stay in the same spot or she feels something. It’s a guy who’s living in like a parallel universe or other side?.. of the same apartment. And I think they eventually become romantic but I’m not sure? I know it’s not a lot to work off but I feel like it was fairly popular. Anything helps, thanks!