Clue: Like tragic Shakespearean couple, they're matched in 26 (5,3,5)
Answer: BLACK AND WHITE
Explanation: Definition: Like tragic Shakespearean couple
the Shakespearean couple is Othello and Desdemona, contrasted in the play e.g. as a 'black ram' and a 'white ewe'
 the connection to 26ac CHESS is in reference to the black and white pieces of the board game