'Why can't a grown adult eat something they don't like? Of course they can. If they choose not to and go hungry instead, that's on them.'
'Thank you, Random! It is rude if people refuse to eat food someone had cooked for them, it offends the cook and is embarrassing for the rest of the diners at the table. Ok so you might not like it, but if it's not going to kill you then just eat up and shut up! It's only one meal (ok so not in the op's case)! '
I'm an ex-fussy eater, and I still have a handful of strong food dislikes, although I happily tuck into most things these days. I agree, if I don't like something and I chose not to eat it, then that's my problem. In most cases, yes I can just quickly swallow something down trying not to chew it, let it touch my tongue or release its flavour/texture I find stomach churning. I don't enjoy the food, but hey ho.
However, there are some things that I simply cannot eat. I'm not being rude. I'm not being awkward. Never mind embarrassing for the cook/guests, it's bloody embarrassing for me and I wish I could just shut up and eat it. But if it's one of the few foods I have a strong aversion to, if I shut up and eat it, then it is quite likely to be followed by my vomiting at the table a few seconds later (seriously) or at the very least with my sitting there with my gorge rising and small amounts of vomit coming up into my mouth to be swallowed down again. That really is what happens. I'm not allergic, some things just turn my stomach. Now that would be unpleasant for everyone.
Why would you want a guest to have to go through that purely as you are too arrogant to believe that not everyone in the world likes what you like? What's actually wrong with a polite refusal? ~I'm not saying there's anything wrong with your food, I'm not saying you are a bad cook, I'm simply saying 'sorry, but I really don't like garlic-fried-elephant-testicles, can I skip on those'.
Why should anyone else care what I do, or do not, eat?
(Ps even at my fussiest I really really enjoyed the food I liked. Someone said fussy eaters just don't truly enjoy food in the way that most people do. I don't think that's true.)