All of these horse riders and "horse lovers" are convinced that horses like to be ridden.
The first horse that a human ever jumped onto immediately thought "Oh, goody, it's so fun to run around with 200 pounds of extra weight on my back". I don't think so. I think it was rather pissed off in fact and therefore the whole "breaking them in" thing from cowboy movies.
People who ride horses think that their love for the horse means that the horse enjoys to have them on their back. If you love horses, run next to them on the beach. The horse will definitely have a better time and you will be in better shape.
We love our children but we don't ride them to school. We don't put big leather things on their backs and pieces of metal in their mouths and kick them in the ribs to tell them what we want them to do.
Now this analogy could go too far - we love our parents but we don't ride them (at least not once we are no longer 3). We love our significant others but ... (hmm, I guess you see what I mean by taking an analogy (if this indeed is an analogy)too far))