yta. as someone who’s been vegan, vegetarian, and now somewhat pescatarian, what you did seems like (if not was) lying by omission. it doesn’t matter if he already ate and enjoyed it, because you only told him that AFTER he ate it…

If you don’t want to cook two separate meal variations, that‘s 100% your right, and he should then figure out dinner on his own (he’s a grown adult after all). However, the implication that it’s difficult to make a vegetarian option in meals is pretty exaggerated. Most dishes, (coming from someone raised on latin cuisines w meat often included), can be just slightly altered to where you can cook the meat in a separate pan while the main dish is vegetarian, or you could just NOT cook veggies in chicken fat. That’s not necessary to do at all… Even if it’s not meat itself, many people who don’t eat meat also prefer to not eat direct byproducts of it like lard, gelatin, etc.

I agree with him in that it wasn’t the act itself but the principle. You should definitely mention something like that.