i would say he should eat whatever he pleases, and tell her that as long as he is not forcing her to turn non-vegetarian, she too should respect the same and let him have what he wants.
if she finds it disgusting to cook non-veg, as many vegetarians do, he can hire a cook or make it himself. that way, he can assure his wife that she will not have to come in contact with the non-veg and he can still have it, without bothering her.
Read more