DELETE statement conflicted with the REFERENCE constraint when updating an entity with a many 2 many relationship (JOIN TABLE)

public int UserId { get; set; }
public string FullName { get; set; }
public virtual ICollection<GroupUser> GroupUsers { get; set; } = new List<GroupUser>();

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public class Article
{
    public int ArticleId { get; set; }
    public string Title { get; set; }
    public virtual ICollection<ArticleGroup> ArticleGroups { get; set; } = new List<ArticleGroup>();
}

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public class Group
{
   public int GroupId { get; set; }
   public string GroupName { get; set; }
   public virtual ICollection<ArticleGroup> ArticleGroups { get; set; } = new List<ArticleGroup>();
   public virtual ICollection<GroupUser> GroupUsers { get; set; } = new List<GroupUser>();
}

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public class GroupUser
{
        public int UserId { get; set; }

        public User User { get; set; }

        public int GroupId { get; set; }

        public Group Group { get; set; }
}

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public class ArticleGroup
{
   public int ArticleId { get; set; }
   public Article Article { get; set; }
   public int GroupId { get; set; }
   public Group Group { get; set; }
}

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protected override void OnModelCreating(ModelBuilder modelBuilder)
{ 
    .....

    modelBuilder.Entity<GroupUser>()
                .HasKey(e => new { e.UserId, e.GroupId }); 

            modelBuilder.Entity<GroupUser>()
                .HasOne(e => e.User)
                .WithMany(e => e.GroupUsers)
                .HasForeignKey(e => e.UserId)
                .OnDelete(DeleteBehavior.Restrict);

            modelBuilder.Entity<GroupUser>()
                .HasOne(e => e.Group)
                .WithMany(e => e.GroupUsers)
                .HasForeignKey(e => e.GroupId)
                .OnDelete(DeleteBehavior.Restrict);

    modelBuilder.Entity<ArticleGroup>()
            .HasKey(e => new { e.ArticleID, e.GroupId });

        modelBuilder.Entity<ArticleGroup>()
            .HasOne(e => e.Article)
            .WithMany(e => e.ArticleKbGroups)
            .HasForeignKey(e => e.ArticleID)
            .OnDelete(DeleteBehavior.Restrict);

        modelBuilder.Entity<ArticleGroup>()
            .HasOne(e => e.Group)
            .WithMany(e => e.ArticleGroups)
            .HasForeignKey(e => e.GroupId)
            .OnDelete(DeleteBehavior.Restrict);
}

public DbSet<Article> Articles { get; set; }
public DbSet<Group> Groups { get; set; }
public DbSet<GroupUser> GroupUsers { get; set; }
public DbSet<ArticleGroup> ArticleGroups { get; set; }

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public bool UpdateArticle(Article article)
{
        var articleGroups = _appDbContext.ArticleGroups.Where(a => a.ArticleID == article.ArticleID);
        _appDbContext.ArticleGroups.RemoveRange(articleGroups);
        _appDbContext.Articles.Update(article);
        return (_appDbContext.SaveChanges() >= 0);
}

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