HI! I work for Delta and that's a really good question that has never been asked. I searched our HR manuels and personel manuels and could not find anything specific. I would think that as long as the employee (retiree) is unmarried and shows you as his companion you would be able to continue to use the passes. I think the best thing you could do, without asking your retiree, is to contact the Pass Bureau via e-mail (they won't take a non-employee call) at
ESC.Delta@delta.com Provide your retiree's PPR number (the nine digit number on your pass card) the date of employement and your name. They should be able to give you a definitive answer.

Hope all that helped! ;-)