UGH

Then read last chapters. He was forced by this organization of theirs to do missions he didn't want and they threatened him to hurt Irene if he didn't do what he was told. Bro was forced to go into a strange world, had no one but her but at the same time she was something others could use to blackmail him. People when being in danger, often distance themselves from their loved ones, they start to be cold, more irritated. Act like they don't care to not be more hurt. Of course it doesn't mean what he did was right but I think it explains a lot. Idk I think we need more of his background to understand him better.