You see there a horse... you quickly notice it was a stallion and was... trying to hide? When he notices you, he whinnies, then like tries to make a step toward you, but then tries to look away, which isn't easy with that wide field of vision.
He seems to be confused and scared, then you notice he was... getting hard? "Is this some kind of sick joke?" you ask looking around... there were some scraps of clothes around.. you recognize them! "Those are Amy's..."
"Yes, they are, and there she is." The man joined you. "She's physically all fine, I think... she's even happy to see you" adds and chuckles, while the horse neighs at him and tries to back off, hide, but there was no place for that.
"Sorry, I shouldn't... And yes, that stallion there, is your Amy." he confirms. "She... is still there, conscious and remembers everything" explains. "She can still answer yes and no"
The stallion looks at you embarrassed and scared. Scared, you ask the stallion some questions and it answers correctly, confirming man's words. Your Amy was really this stallion!
"Come, I will explain everything" he says and pulls you away.
When you were far enough, he starts explaining: "You see, our farm is in possession of some so-called cursed halters." starts, you weren't able to say a word, still shocked by the realization. "We normally keep them closed, but Amy working here has access to... most of the stuff. She found one of these... in their normal state, they look like they were made for humans, but once you put them on, you start changing into a horse." says.
"B-but why do you even have such thing? Can she turn back? Can't we just take it off?" you ask quickly.
The man sighs and explains "No, it's not that simple. Each halter has assigned challenge to do. Win, you can change back and get some... abilities or reward. Fail it, and you are stuck like that for the rest of your life and the world will forget about you. You were lucky... or unlucky I've managed to contact you before she disappeared from your life too, because you see, she put on..."