IMO, it’s a form of mental illness. My mom won’t eat anything if the texture doesn’t feel right in her mouth. She is malnourished and only weighs 90 pounds. She has all kinds of digestive issues, heart issues, high BP, and almost all of it is caused by her diet. She’s in her mid-80’s but was relatively healthy until she started disliking the feel of certain foods in her mouth. The doctor says it’s all in her head. She wasn’t that bad when she was young but after she hit 75 or so it really got bad.
OK, I wish her the best. Hopefully she can find enough to like to stay healthy