While I do feel Maek should be told, the whole idea of 'slapping' him is really annoying. He wanted to use a condom but Fah said it was her safe day, so he is a responsible person, not his fault she got it wrong or whatever. Plus, the fact that Fah is doing all this for his future implies that he would throw it all away for her and the baby, so this makes him a great guy. As such, I don't agree with Mod treating him like the villain. He should be told. He should definitely help. But he isn't a bad person.