For starters, Mr. Vegan/Too-Much-Saturated-Fat needs to start being considerate of your time and budget.
He needs to learn to cook for himself, and pay for his "special" food, if he's creating stress and a hardship for you. As an objective observer, it's almost as if he is trying to see just how far he can go with this BS of his in puppeteering you. You went, imo, to an extreme to accommodate him by purchasing things way too expensive, and going to way too much effort to please him, and then he turns around and finds fault, and shows a complete disregard and lack of appreciation for the effort and expense you went to for him.
My advice: buy some dry beans and lentils and brown rice, and use them to make a couple of different pilaf recipes a couple of times a week. Keep lots of fresh fruit and veggies in the house.
For my vegetarian daughter, I make vegetable broth by roasting herbs and vegetables (toss with some canola or olive oil and roast at 425°F for 30 minutes) that I would otherwise throw away when I'm cleaning out the fridge - still edible, but not as fresh as can be - and then dump them into a crockpot filled with water and let simmer for a few hours. Then I strain and divide into containers. One container is to make soup - I throw in cabbage, carrots, beans and whatever vegetables I have on hand, a can of diced tomatoes and a can of navy beans. Sometimes I add tofu, sometimes I add leftover rice or potatoes. It's her favorite soup, and it takes very little effort on my part. In fact, sometimes I'll double the batch and make half with chicken or sausage pieces for the rest of us, with some homemade buns, and we're a happy bunch. The other containers of broth can be frozen or used to flavor rice or pasta.
But seriously, he needs to be taken down a couple of notches. I don't like how he's abusing your resources and your generosity. It won't kill him if you go on strike for a week or two. He'll figure it out.