BTW, If you don't want to cater for vegetarians, then don't invite them round for a meal. No need for drama
No drama involved. Our vegetarian friends are too well mannered. Life is built on blind eyes and minor hypocrisy but I have to say that using dairy when it's based on one of the more questionable aspects of the food chain is up there with the best.
I understand those who like meat but avoid say, veal, also people who avoid red meat but enjoy free range poultry and folk who eat fish but not other animals. We all draw our own lines. If you drive a car you'll kill and maim small and large animals and, in my experience, most would rather the creature wanders into the hedgerow for a slow and painful death than despatch it cleanly.
It is possible, indeed necessary, to develop a moral framework around animals that sees them other than completely alien or pet fodder.