Given these entities:

public class StoredArticle
{
    public int Id { get; set; }
    public string Title { get; set; }
    public StoredTimePeriod TimePeriod { get; set; } = null!;
}

public class StoredTimePeriod
{
    public int Id { get; set; }
    public string Name { get; set; }
    public DateTime Start { get; set; }
    public DateTime End { get; set; }
}

I want that Article and TimePeriod have a one-to-one relationship. As I understood TimePeriod is the principal and Article is the dependent, because it’s having the foreign key pointing to TimePeriod

This is how I setup their relationship:

modelBuilder.Entity<StoredArticle>(entity =>
        {
            
            entity
                .HasOne(e => e.TimePeriod)
                .WithOne()
                .HasForeignKey<StoredArticle>("TimePeriodId")
                .OnDelete(DeleteBehavior.Cascade);
        });

With this setup, following happens:

1. When removing the Article, the TimePeriod remains in the database
2. When removing the TimePeriod, the Article is removed too (cascade)

But I want it the other way around. And I don’t wan’t to add ArticleId to TimePeriod, because TimePeriod is used also in other classes.