How do you explain to a horse that you are doing this because you love him?I would recommend lots of TLC when you aren't treating him... petting, scratching, grooming (if he likes that), extra treats, etc. It should help reassure him that you aren't being deliberately mean to him... or at least it will confuse the heck out of him.
That is what I am trying to do... I am trying not to be all business and take a bit of extra time to rub is face, which he likes. He just doesn't understand why I keep suddenly doing something mean right in the middle of it. LOL! It is rough... normally he gets one or two shots a year and wormer only every two months. Normally and there is lots of time between unfair abuses!