I watched it a long time ago, stopped somewhere in the middle, and forgot all about it... until now. 

From what I remember, though, it doesn't have many episodes. The plot started with a girl who discovered that her boyfriend was cheating on her and decided to move out. She eventually rented a room in this house, along with three other people (1 girl, 2 men), one of which was her first love (Or childhood crush? I'm not sure... RIP). The guy was the typical handsome and cold male lead, and I think he still liked/adored the MC (albeit secretly)...? Anyway, I might be wrong, but I recall that he had one problem: he couldn't get it up (??? Again, not sure). I forgot the process, but somehow he sneaked into the MC's room and started h*mp*ng her? IDK. Then I stopped, because I had to study, haha...

As you can tell, it's a mature drama. I don't think it has nudity, though. Maybe in the later episodes, IDK... but I really want to watch it again. It was pretty good.

Anyone please help me find this drama. I'm desperate! ? Thank you! Have a great day. ♡

Kakafukaka maybe??

YES!!! WOW, that was fast!!! Thank you so much!!! Apologies for my inaccurate description ??

It was actually a pretty good description. Plus it was the first JDrama I ever watched and I realised as soon as you said he couldn't get it up unless he was with her :)