Okay, so my memory is terrible and I'm not entirely sure if this was a kdrama or a reality show type thing, but back when Dramafever was a thing (rip uwill be dearly missed), I remember clicking on this show but never really finishing it. 

It was basically set in an apartment building, and the main theme was cohabitation. It featured a few different couples, and two male roommates who had just moved in together, one of which was Japanese I believe. I think they were possibly supposed to have a BL storyline but I never finished it so I'm not sure. 

I know this is asking a lot since I don't remember much, but if anyone happens to know what this drama is called, I would be forever grateful!

Maybe The Lover (haven’t seen it but I know it takes place in an appartment with multiple couples)

Description: 
The series talk about four different couples living together in one apartment complex.
Both in their thirties, Oh Do Shi is a voice actor and Ryu Du Ri is a blogger. They simply chose to live together instead of getting married, and have been sharing an apartment for two years.
Jeong Yeong Jun and Choi Ji Nyeo are a couple that's twelve years apart in age. Ji Nyeo has the personality of a penny-pinching ajumma and basically supports her younger boyfriend in the hope that he will someday realize his dream, while Yeong Jun is an unemployed musician who carries around a guitar he doesn't know how to play. They've been living together for a year, and are quick to fight and make up.
Park Hwan Jong and Ha Seol Eun are in their twenties and have just moved in together. Seol Eun wants her boyfriend to believe that she's the perfect embodiment of femininity, and works tirelessly to keep up the illusion.
Lee Jun Jae is a loner who prefers to stay at home, but is forced to find a roommate for financial reasons. He doesn't even want to exchange unnecessary small talk so he advertises for a foreigner who can't speak Korean very well. Enter Takuya, a Japanese guy on his travels. Takuya thinks Jun Jae is wasting his youth, and begins to draw him out into the world.

yep, Rien is right, it must be The Lover!

Yes you're right, it's the Lover!! Thank you so much!!