It has been said here that an invitation is not a summons, the OP can just decline the invite. But the host has the right to serve the foods she prefers to. It is not polite to bring food to someone else's house. It is especially not polite when one knows the host would not feel free to decline this honor but would be silently fuming as in the OP.
People go to restaurants all the time and order appetizers and a salad, so expecting someone to either fill up before the party ( or after) and have what she can of the offerings or decline the invite, is not so heinous of the host. It is after all, what would be expected of anyone who did not like the what host had to offer if the situation was reversed - or if the meat eater simply did not like the entree.
Oh, I see the difference. When I invite friends over, I don't care about the specific menu, I care about my specific guests, and helping ensure they have a good time. I am eager to tailor the menu accordingly or welcome contributions they really like to bring. I don't feel it hurts my cooking at all to make adjustments or accommodations. I always feel the point of socializing over a meal is the friendly and comfortable socializing, and making sure my guests are happy and feel welcome, not the specific food items involved.
I assume your friends have realized that you consider non-disruption of your meal planning to be your major concern (as you prefer they not attend and/or participate rather than disrupt your planning), and in that case, great, I'm happy that works for you.
I agree. Snowdragon, it seems you have a bit of a double standard here. In one post you say that you make a variety of vegetarian dishes you could prepare for a guest and in this one, you say a vegetarian guest should be happy with salad and appetizers. I ask my hosts what they would like ME to do so they don't end up in that silent fume. I'm assuming that somebody who wants me to come to their home can be honest enough to say "I have a menu already set, but I'll have some appetizers and salad you can eat."
Maybe Snowdragon means that as a hostess she would provide a variety of vegetarian friendly food, but as a guest she would not expect her hostess to rearrange her menu.
precisely. The insult I see here is pre-emptively asking ( or not asking at all) The OP stated that her hostess would acquiesce but would silently fume about it.
From post #1. "Lets assume the hostess is uber polite and would not tell you that she minded either option even if she was actually steamed about it."
So it's known the hostess would not feel she could refuse, even if she minds. SO the polite choice is not to ask and not to bring something, eat what you ( general you) offered. A hostess has enough going on with out someone bringing extra food either for the hostess to cook - or put an extra body in the way of the preparations for dinner, by cooking themselves a separate meal - is rude.
The hostess was kind enough to tell you (general) the menu, either accept it or decline it, but bringing another meal because you find their hosting lacking is rude.