The uke is afraid of darkness because he was punished by being stuffed in a dark closet as a kid. It was so severe that he can't sleep without someone with him so he finds lots of partners before the seme comes along.
http://www.mangago.zone/read-manga/makkurayami_de_kimi_to/
Don’t forget to read squel. It is better
http://www.mangago.zone/read-manga/code/
I actually really liked how it's a bit more open ended and how it didn't have that sort of grand almost over the top ending. I feel like it was wrapped up well showing that the seme is making an effort and that things are going good. However I will agree that more chapters would be nice.