i'll probably be npcing his wife because i haven't found someone to pick her up yet. but, i had a few possible ideas for his mistress(es). one idea had been someone significantly younger, but i really love the idea of someone a little older, and nearer his age.
perhaps, they had been engaged when they were younger? when she was born, and he was a young child? a la princess aurora and philip, lol. his father could have arranged the marriage because at the time harald's older brother was the presumed heir, and marrying his other son to the heir of another house was just a grand idea. when ryder became problematic and harald was chosen as heir ... things changed. the engagement was broken because it wouldn't be too effective for two heirs to marry. so, he ended up marrying a girl from one of his banner houses.
they might have developed a friendship/understanding since they are both the heads of their houses. she is a widow now, and their friendship can become something else?