To anyone who is wondering why the player wouldn't just tell her big bro abaot the cheating bastard, I think it's because this arc is more on the granting the victim's wish to make them (the bastard and the bitch) to regret it for the rest of their life, so if she use the big bro immediately it might be to good, I mean the big brother looks like he wants to just kill the bastard which is to good for him, he needs to "regret" it for the rest of his life in order to fulfill the victim's wish..
Besides this arc seems kinda different than the ones before, notice it that before the MC come to this world there's a system notification that said EMERGENCY, while the ones before just like the next destination have been selected..