Question: How long have the authors of the book series with the fictional protagonist Fiddler been married? 
Sentence (from "Fiddler (mystery series)"): The books in the series are "Just Another Day in Paradise" (1985), "The Frog and the Scorpion" (1986), "Gatsby's Vineyard" (1987), "Just Enough Light to Kill" (1988), "The Art of Survival" (1989), "Money Burns" (1991), "The King of Nothing" (1992), and "Murder Hurts" (1993).
Relevant evidence: No