horse becomes dumb?

i dont know if anyone has asked about this or if i am being too careless with my horse but why does my horse start to become suddenly more dumber? when i do small obstacles or close to a tree it will suddenly hit the obstacle and lose health. This seemed to happen when i have max bonding, like the other day my horse flew in the air from a little broken tree in the ground. Is this normal?? and also when i stopped on a cliff the horse moved by itself and both i and the horse fell down ?