Kakko Warukute Kakkoii Kimi

From Bliss:

Ever since they were little, Yukihisa and Takashi have always been together. However, Takashi recently started acting strange towards Yukihisa. Takashi refuses to come near Yukihisa, baffling him. Takashi offers no explanation for his actions, causing Yukihisa to be filled with doubts about their friendship. What can Takashi be hiding from Yukihisa that's causing him to keep one meter away from him?