what manga/manhwa/manhua/anime/novel etc. that has been discontinued, cancelled, axed, or abruptly stopped that you still grief about to this day. mine will always be YOI, mappa never made an announcement but there's no doubt they've definitely dropped it.
I think Onborobachi? It's been 84 years since the last update
Also YoI but we don't talk about it in this house because grandma (me) gets emotional (murderous) reply