As others have noted, there is no rule regarding turn times. (Some people believe that, when the box says "60-90 minutes", that this is one of the rules of the game; but this is not an actual rule.)
Etiquette says that you should make the game fun for other players as well as yourself, and making your opponents sit there for several minutes while you debate the pros and cons of five different cards is not "making the game fun" for them.
This being your wife makes it a difficult situation. There are people that I simply will not play games with any more. Other times, I will break out my iPhone and play a game (yes, a game) of Gin Rummy or Cribbage while I'm waiting for my turn. You need to find a polite way to express to your wife that, when the "whose turn it is" counter is 75%-25%, this stops being a fun endeavor for you. And I wish you the best of luck in figuring out how to do that. :)