The big thing that is really needed in marriage, imo, is arranged marriages. Bethroth your children and then forget about it till they are of age. Major penalties, possible claims if these are broken.
The marker of married on courtiers is a good idea as well that would avoid clutter.
As far as AI selection of marriages I think it should be a priorty of:
1. Station - similar or only one step away. (Dukes marry their children to other Dukes, kings if they can, counts if no other choice or want to secure loyalty. Esp. for older children, less important for younger children in large families or bastards)
2. Proximity - within realm or neighboring realm only. Exception: Emperors, Independent Kings and Dukes
3. Culture - important, but that much during this time.
The marker of married on courtiers is a good idea as well that would avoid clutter.
As far as AI selection of marriages I think it should be a priorty of:
1. Station - similar or only one step away. (Dukes marry their children to other Dukes, kings if they can, counts if no other choice or want to secure loyalty. Esp. for older children, less important for younger children in large families or bastards)
2. Proximity - within realm or neighboring realm only. Exception: Emperors, Independent Kings and Dukes
3. Culture - important, but that much during this time.