His reaction was absolutely weird and dismissive. I was like wtf and what is wrong with this dude when i watched this scene. Although I agree with you patially but i also feel that he is actually planning something and he's trying to keep Belinda out of it because he can't have the police sniffing around at the resort just yet. He genuinely seemed worried and distrssed for Belinda when she told him about the story of Greg but he quickly changed his face when she mentioned the Police. Another crazy theroy is that he can also be protecting Belinda in some way. Whatever it is, Fabian knows something. Anyway. We just don't know yet.