Aww, that is so cute. I often think how sad it is to be a horse in a relationship and all of a sudden your owner sells you or your friend and you never see them again. I had a mare that was in love with a friends gelding. They were joined at the hip, all the time. They would call to each other if one was away for a bit. One day my friend decided to move her horse elsewhere and my mare was lost. There were several other horses there but not her friend. Luckily, her friend returned after a few months and they immediately picked up where they had left off. Their bonds are very real, that is for sure.
Glad your guy looks so wonderful now, you are doing a great job. So nice to see him happy with his friend by his side. :)