?? There many a times Shiou did whatever he wanted and because of that Michiru gets confused and mixed feelings. Shiou willy nilly changes his mind all the time. Even I got frustrated, he was like an over-emotional selfish teen that did what he wanted, never telling people about it nor wanting to talk about it. He was a child.
Even Michiru would prefer tot talk things out but if anything goes south for Shiou he will decide everything for himself without caring about others at all. When he moved out, he didn't even tell anyone. He always feel like a child going on a never ending tantrum and I wished for one single moment he thought about talking his feelings out instead of CONSTANTLY running away/doing everything on his own/making people guess at his actions.
Michiru is a hard person to please. I can really understand Shiou's frustration, and there are times when I feel like Michiru simply doesn't understand that what he does hurts his brother. Yet, he still acts very annoyingly cold at times, and blames the problems on Shiou in their relationship.