For myself, if you're going to invite people to your home for dinner, I think you cook something everyone can eat. Otherwise you make one group of people feel like an imposition. I have vegan friends and I think if they were coming to see me, I'd cook something everyone could eat. As a vegetarian, I hate it when there is one dish 'for you' and others for everyone else. I think it is rude. It feels rude, and it's more of an obligation to be there than an enjoyment. I'd never ask anyone to bring their own food with them!
Wow. Hoe entitled. I cook for friends very frequently and I would NEVER expect the entire group to eat vegetarian or vegan for the sake of one guest. I am very happy to cook a seperate main for them, I don't expect them to just pick around the side dishes and make the best of it, but NO WAY would I expect the whole group to go meat/dairy/egg free. I want people to really enjoy the food I make them and as inventive as I am, dedicated meat eaters almost always feel there is something missing in a vegetarian meal and especially a vegan meal. It's not so much the slab of meat itself, it's the way meat changes the flavour and texture profile. Even a really nice veggie dish can often end up feeling like a fancy side dish rather than the main event. It can taste a bit one-dimensional in comparison to a dish where meat or fish have been used - even sparingly. With vegan food that is magnified x 1000 in my opinion. And then there's the frankly bizarre and unpleasant things vegans use to subsitute and replicate cheese and meat and butter etc. Urrgh. Just no.
I eat quite a bit of vegetarian food out of choice but I love cheese, I love lentils and beans, I love mushrooms, I love squash and beetroot and almost all vegetables - not everybody does.
What I often do is something like curries, so I can make a meat, fish and a veggie one and anyone can have a bit of any of them. That way it doesn't draw attention to the fact that one person is being served something separate.
But depending on the occasion and what I wanted to cook, I wouldn't think twice about serving one separate dish to the veggie/vegan. My SIL is not a veggie but is a very fussy eater who hates garlic , wine, onions and any trace of spice. I always cook separately for her. There is NO WAY I am inflicting some bland, substandard nursery food on the whole table just because one person eats like a child. And it's the same with vegans or vegetarians.
If I got the vibe that you found that 'rude' I'd not be cooking for you again. Problem solved.