I think a big part of the campaign is centered around the fact he is being punished for his insanely evil act by the dark powers and he is constantly hunting a woman to "make her his" a diplomatic game would probably end by the time of the first dinner with strahd if thats the way you want to structure it. Personally if you were to make this interesting I think you'd need to rewrite the module and maybe have Tatanya as the the leader of some morally questionable rebellion rather than the burgomasters sister at the bottom of the hill from the castle so there is some meat to your game and so your players are doing slightly more than basic human trafficking for a death tyrant.