A friend of mine had a horse who developed this habit after he got a bad infestation of ear mites while in rehab for a suspensory injury. He never got over it entirely, but she did find ways to work around it. For one, she rode without a browband because he hated them. For two, she would put the bridle on like a halter (buckling the side piece), and sneak the crown piece up his neck while he was distracted with the bit or a treat. Eventually she got to where she didn't have to sneak the crown piece up his neck, but she never was able to go back to putting the bridle on like normal.
My horse has this issue as well. What I’ve found helps is petting their face often, brushing their forelock near their ears and their neck just behind their ears. Brush your hand along his ears briefly and continue to do this whenever you bring her out. Over time, she’ll learn she can trust you and allow you to touch her ears. I hope this helps!
I had a similar thing happen with my horse. We would just play with his ears for a few minutes each day and slowly he got better. If she doesn’t improve or gets worse you should have your vet check them