Sounds like my D. I always thought she was just kidding when she was younger, but she told me recently that it’s actually pretty important to her, almost like an actual phobia. Certain foods can touch if they’re intended to, e.g. gravy and potatoes, while others can’t, e.g. vegetables and gravy. She’s not a picky eater at all otherwise and eats all kinds of different cuisines.
Ah, here it is. Looks like it’s a thing:
“The fear of foods touching—formally known as brumotactillophobia (try saying that ten times fast)—comes in varying levels of severity and is believed to be a mild form of obsessive-compulsive disorder (OCD).”