I doubt the prince has truly realised anything. His fundamental mistake is thinking the saintess should gladly sacrifice herself for the country, as if it was the greatest honour in the world. What he now, probably, believes is that his mistake was pressuring the saintess so much that she ran away. So, basically what he'd want to do now is to keep the saintess sacrificing her whole life for the country, without expecting much in return, but he just needs to keep her level of work at a level where she won't run away. Not much of a self-reflection breakthrough.
Of course I could be wrong.