Yeah, I get this sometimes.
I eat a lot of breakfast cereal but sometimes even that's too much especially when I'm too tired to chew so then I'll take chocolate almond milk, a banana, and a little oatmeal and blend it to drink.
Like someone said nuts or even a bit easier, smooth nut butters are good protein. (You could also add the nut butters to the smoothie posted in the last paragraph. I did that with my Mom and she liked it. )
You could also do healthy soups that can just be reheated and even blended to a drinkable mixture.
Yogurt is good. If you can't do cow's milk they have all sorts of other kinds now too. I do sheep yogurt with a little Crofter's fruit spread or jam mixed in.
There is also goat yogurt, cashew milk yogurt, etc. Or you could do the Kefir which is like a liquid yogurt.
I think they also make oatmeal cups in different flavors that can just be mixed with hot water or maybe mixed with water and cooked in the microwave. I'm not sure how those work.
One more idea is beans. I found a molasses baked bean recipe that we liked. Beans are protein, carbs and fiber all in one. You can use a food mill to remove the skins if you have IBS or diverticulitis type issues.
This is probably going to get me warnings from the high-cholesterol police but bacon. I just found that Hormel makes a pre-cooked, uncured bacon. I wish it was also antibiotic free.
There are other brands out there that probably are, but I react to smoking, cures and vinegars and those are used in many of the others.
Also Jones brand makes sausages that are precooked as well that don't have a lot of other things in them.
Bacon helped me put some weight on my Mom when she was still here. That and putting some gluten free cookies in a cup on her desk/table.
That's the other thing. As long as you don't have food sensitivities and reactions to things, get the foods you most crave. That might help you feel more like eating.
Also if you can afford to maybe think about putting a small refrigerator and micro in your room so the food is very close by when you do wake up.
If you have any resale shops like Restore around, your wife or maybe another family member could probably get them used less expensively that way. Goodwill's might be good for blenders and smoothy makers as well.
Sorry for the long post. I would try to organize it but I can tell my brain isn't going to let me right now.
Hope you find things that work for you.
Edit: Thought of something else. Cheese is high calorie but easy to eat a chunk. Throw in some gluten free crackers and you have some carbs too. And you can get other types of cheeses besides cow's milk as well.