mirastrophe
noun
The sensation of dedicating countless hours to meticulously crafting a plan, accounting for every possible variable, only to witness the final product diverge from your expectation, leaving behind a quiet ripple of disappointment.
From Latin 'mirari' (to wonder) + Greek 'strophe' (turn), denoting a turn from wonder to disillusionment. Pronounced "mee-RA-str-oh-fee"