Doubt it if it's the average non-Christian Japanese household. Probably saying something like "Mataku" which is like verbalizing sighing in exasperation.
She did actually, you see it in an earlier chapter as to why she becomes such a raging bitcharooni-dooni to him to overcompensate for his brother leaving, which is also why his relationship with his brother is not great
Man so many chapters keep looping back to how much of a bij the mom is eh
@johnny_average No, not really. I don't have the raws to verify what was used in this context but I wager it was probably some variant of まったくもう/mattaku mou to express their frustration.