Ash instinctively wanted to say "Tell us about your misfortune and let us have a laugh," but he suddenly remembered his promise to the Witch not to pry into her life, so he swallowed the schadenfreude right back down his throat.
He was someone who took promises very seriously, perhaps because his father had bought him a gaming console after he scored perfect hundreds in elementary school, or perhaps because he had seen his beloved elder brother top his grade, leading their father to withstand the teacher's pressure and allow his early romance.