Most cultures where vegetarianism is practised widely are 'lacto-vegetarian' - i.e. they include dairy products (milk, butter, cheese, cream). This is a good way of making up enough fats and proteins that you are missing without meat.
But ethically it makes no sense to me, as I think it'd far less cruel to kill an animal outright than to systematically impregnate a mammal, then separate it from its young and steal its milk. If we are saying that animals have feelings and thus should have rights, that's cruel and unusual torture to my mind. I say this as someone who eats both meat and dairy, but found myself questioning the ethics of the latter while glamping on a (very small, family run, apparently 'ethical') dairy farm and seeing the baby calves suckling on each other for comfort in the absence of their mothers, and seeing a mother cow literally bellowing at us as she was led to the milking barn as we were standing next to the calves' pen - it was so obviously protective and what a mother would do, I identified with it and haven't felt quite right about dairy since.
I don't understand vegetarians from an ethical POV - how can you be not on board with killing an animal (troubles then over) but fine with mothers and babies being systematically separated virtually at birth and made to go through this over and over again for our benefit? Vegans at least make sense ethically, except on the matter of eggs - an unfertilised egg is basically a waste product for a chicken, so what harm in eating it?
I also think that there is dissonance with being an animal lover and thinking eating animals is immoral - are only humans obliged to morality? And if so why? Is it because we are actually different to other animals in terms of our intellect and feelings - which somewhat undermines the whole argument that animals are the same as us and therefore shouldn't be killed and eaten? Nature includes carnivores and food chains - yes our development of farming has put us outside of that, but surely there is a way we could continue to participate in those cycles, if we accept them as legitimate in other animals?