If on the calendar, it looks like a mare should be in season, and she is walked within 15 feet of a breeding stallion with no response, could she be in silent heat or just not in heat?
Stallion paid attention for 30 seconds and went back to his hay.
Mare could be boarded in a corral across the aisle from the stallion if this would help getting information.
Even if the maiden mare is shy, wouldn’t the stallion be reporting what he thinks of the mare?