We had SIL and her partner round to Sunday lunch yesterday.
They are vegetarians so I cooked a vegetable and bean tomatoey stew. Planned to serve it with jacket potatoes (our stove is in its dotage and only 2 hob rings actually work, so needed to cook potatoes in the oven so room on hob for vegetables and stew)
DD struggles with jacket potatoes, so was going to remove the insides of hers, mash them with butter and cheese and then stick them back in the skins. So I thought I would ask if anyone else would like their potato done the same way, and it emerged that SIL's partner (aka the world's fussiest man) doesn't like jacket potatoes OR mashed potatoes - even when not put back into their jackets. And he doesn't like couscous either. So was wracking my brains and thought of roast potatoes, which were deemed acceptable, so shoved some goose fat in a baking tray, stuck them in the oven, Bobs your uncle, everyone enjoyed lunch.
Was only this evening, whilst complaining on phone to friend about fussiness of guest, that it suddenly occurred to me that goose fat is not strictly vegeatarian .
Now if they were veggy for religious reasons, or medical ones, I would obviously have to tell them. But it is because they are animal lovers.
AIBU not to tell them? It was a genuine mistake, it seems a bit late to tell them, there is nothing they can do, so I'll just be spoiling their evening (and possibly making them feel slightly sick) for nothing.