I have the ultimate edition. Bought the thoroughbred in Valentine and stabled the Shire. I assume the starter Tennessee walker was also stabled but didn't check. Began using the thoroughbred. I've never had a horse die that I know of. Riding along I hear some drunk guy singing at a camp. He had his horse there. I sat with him and listened to him ramble on. I get up and get on a horse and ride away. I jump off my horse to chase some deer around then whistle for my horse. A Tennessee walker comes up to me....wtf... I ride back to his camp andy horse isn't there. Did I ride his horse by accident? I have no clue. Ok, back to Valentine (the only stable I have used this far). My horse must be there. Nope. In the stable is the starter horse, the Shire, and then another Tennessee walker (my active horse). If I got on the wrong horse, why is this new Tennessee walker wearing the special edition saddle that I bought at the stable and put on the thoroughbred? I never once took the saddle off of the thoroughbred.
I paid to use this horse and expected that I would have it throughout the game.
Also, I had only ever used autosaves up to this point so loading an old save to work around this is not an option.
I don't know if getting a refund is possible at this point but this would have absolutely been a deal breaker for me had I known that I could lose the horse.