The boar acts on its own and quite cautiously in the presence of the red deer.
Camera viewers may have noticed that the red deer have gathered in groups by gender that act and move together. The boars have no desire to compete with such company. They wait until the deer have business elsewhere and the feeding ground is free.
Image from webcam captured by Hagnat, LK forum
The temper of the red deer has calmed down after the matings. Sometimes a couple of equally strong stags cross their antlers in order to determine their rank in the flock hierarchy. But generally the group knows who, where and how to behave.