Arashi,
Concerning DC's apparent decision to only occasionally show the ghosts of Beth and Quentin together, I guess it's a case of less is more, and more is less.
The great film director Howard Hawks believed that it was more frightening to only briefly show the so-called "Thing" in the sci-fi classic, "The Thing From Another World."
Bob the Bartender, who believes that actor Bob O'Connell (Saloon Proprietor Bob Rooney) had more lines in one scene as a doorman in the incredibly schmaltzy "Love Story," than Mr. O'Connell had in an entire year's worth of Dark Shadows episodes!