Following the Moon

From Shinmakoku Scanlations :

"When was the last time we even spoke to each other...?"

Koto Takuya knew bad things had happened in Yukihisa's house next door, ever since they were both children. But Yukihisa never asked for help, and Takuya was too timid to do anything. Now Yukihisa is nowhere to be found. Was it wrong that Takuya had stayed quiet?