It's a BL... but I don't remember what's the title, nor I remember if it's a manga or webt...

It's a BL... but I don't remember what's the title, nor I remember if it's a manga or webtoon.
I just remember this bit from the character. He could only sleep on the left side of the bed. There should be a wall on right side, if not the character would roll in his sleep and fall off the bed.
So this love interest/housemate of his would sleep on the same bed as him, but on the right side to prevent him from falling off the bed.
Anyone have any idea?