And he never gets to meet his dad
Its just like weaning a litter of puppies from their mom. By the time the puppies are eating on their own, have teeth and bite and need to move on, mom is only happy to have the little ankle biters gone. Matter of facts of life.
I know that this is not feasible for the big farms...but there are ways for the process to be kinder on the mare and the foal. If you watch the PBS "Nature" program on the Lipizzans, you will see what I think was a much better weaning process than what we seem to do in this country. The foals and the mares all run together in a herd setting from the spring when they are born until the late fall. Once weaned the colts and fillies run together in a herd throughout the winter.