CREATE TABLE ActionEmp
( ActionID int
, EmployeeResponsible int
)
;
go
INSERT ActionEmp SELECT 1, 12345;
INSERT ActionEmp SELECT 2, 67890;
INSERT ActionEmp SELECT 3, 54321;
INSERT ActionEmp SELECT 4, 09876;
go
CREATE TABLE Actions
( ItemID int
, ActionID int
)
;
go
INSERT Actions SELECT 1, 1;
INSERT Actions SELECT 1, 2;
INSERT Actions SELECT 2, 4;
INSERT Actions SELECT 3, 1;
INSERT Actions SELECT 3, 2;
INSERT Actions SELECT 3, 3;
GO
SELECT
  a.ItemID
, ae.ActionID
, ae.EmployeeResponsible
 from ActionEmp ae
   LEFT OUTER JOIN Actions a
     ON ae.actionid = a.actionid
 ORDER BY 
   a.ItemID
 , ae.actionid
;     

CREATE TABLE Actions
( ActionID int,
  ActionName varchar(30),
, EmployeeResponsible int
)
;
go
INSERT Actions SELECT 1, 'Emails Sent', 12345;
INSERT Actions SELECT 2, 'Emails Archived', 67890;
INSERT Actions SELECT 3, 'Project Folder Archived', 54321;
INSERT Actions SELECT 4, 'Acknowledged Notification', 09876;
go

CREATE TABLE Items
( ItemID int
, ActionID int
)
;
go
INSERT Items SELECT 1, 1;
INSERT Items SELECT 1, 2;
INSERT Items SELECT 2, 4;
INSERT Items SELECT 3, 1;
INSERT Items SELECT 3, 2;
INSERT Items SELECT 3, 3;
GO

; WITH AllActions (ItemID, ActionID)
AS
(
SELECT distinct
 i.itemid
, a.actionid
FROM items i
  CROSS APPLY
    ( select a.actionid
        FROM Actions a
    ) a
 
)
SELECT
* 
FROM AllActions aa
WHERE aa.itemid NOT IN (select i.itemid
                         FROM items i
                         WHERE aa.itemid = i.ItemID
                         AND aa.ActionID = i.ActionID
                        )
ORDER BY
   itemid
 , ActionID 

Select a.ItemID, b.ActionID From 
	(
		Select Distinct ItemID From Items 
	) As a 
CROSS JOIN Actions As b 
Except 
Select ItemID, ActionID From Items