I would get his vision checked, and is eye muscle workings by a behavioral optomitrist, just to be sure.
I wonder if he overheard a babysitter, or an adult or a friend saying something about his reading that he misunderstood. It's not infrequent that he will misinterperet a comment.
My DS wasn't an early reader, but he was an early perfectionist, and would demand to sit on my lap and direct my hands to draw wild pictures instead of his babyish scribbles.
This would be a great time to get some really good individual professional help, although I don't want to suggest that it's an emergency, not so much for the reading, as for the perfectionism and the low frustration tolerance. My son is a very intense guy, and maybe always will be, but I sure wish I had worked out some parenting stratagies to deal with this earlier - you are miles ahead of me.
One idea is that it might be a level problem? What level of books he want you to read to him? I would bring home a book that's many levels above what he was last reading,(( like "Mrs. Pigglewiggle"? or "My Father's Dragon"?)) and start reading it to myself, and see if he sneaks it. Or you can misread a word and see if he corrects you. Have you tried large print Harry Potter? At least when you read to him, what books does he seem to enjoy?
I hope someone here has lived through this, but my understanding is that many have some level of immature eye function, immature relitive to their reading level, that is, not their age, and some are very stubborn kids.
Love and More Love,
Grinity
