lol bless, you will have to break it to him gently so you can get it exchanged! Least it was something good though, could you imagine if he presented you with a dayglo plastic bridle thinking you could go out showjumping/dressage in it
My now ex OH was frightened of the nags at first, but having decided that the only way we were going to spend any time together was with the horses he decided to join in, he learnt to ride and got his own very quiet hack! Can you make a joke of the wrong size thing and help him to exchange it for the right size? something like the mare looks smaller to him because he stands further away? Just a thought.