I don't want my wife to make her favorite comfort food
That's peculiar if you ask me. Who wouldn't want comfort food?
I think comfort food makes people even more depressed.
That's your opinion! If she wants to have some comfort food, she can! Nothing says you two need to like the exact same foods.
Well that's your opinion! I don't think it makes her happier and if I want to tell her what to eat I can.
It could be true for you that comfort food doesn't improve your mood but what's good for one isn't good for another, even in a relationship. You also shouldn't feel you have the right to decide what type of food your wife wants to eat. So if you don't want to eat that food its okay, but you need to let your wife do what is good for herself.