Deleting won't nullify until save : is it true?

Question

My situation : I have complex (24 entities, many relationships and many ordered to-many relationships) model in Core Data.

Now let\'s say, I have an entity

Answer 1

For a reason, the graph of the entities was not coherent (some bug of CoreData I guess, the relations and their inverse are not properly maintained). So, it refuses to delete the object. If I save, it first makes the graph coherent and then it is possible to remove the object.