For a long time, it didn’t occur to me that horses had friends.
I would notice my horse was often standing near another particular horse when I’d fetch him for a ride and I’d notice they’d often whinny to each other as we walked off. But, my play with my horse was never on his terms. I never lingered in his pasture or played with his friends. I was very me-centric.
It is often easy to see who your horse likes most in his herd - they’ll be standing near each other whenever you look. They’ll be dining or having a drink or relaxing under a tree together.