Well, if they want to mad at him longer, it better be for a better reason. Truth to be told, Ichika doesn't do anything wrong to them this volume except not telling them about Tatenashi's request. It's Ichika's business who he wants to team up with, why do they have to be mad to Ichika for rejecting their request? Although, I agree with the point that having member of his harem mad at him seriously will be a good change of pace