Wolff Gunsprings sells reduced power springs for Ruger Revolvers. A gunsmithing outfit like Gemini Customs, LLC can bring the trigger pull weight down for you, too. (You don't need to spend, 'big bucks' on an entire modification package.)
Just out of curiosity, is your wife firing double-action by, 'staging' the trigger? If she is, then that would make it more difficult for her to pull the trigger.
By the way, my very feminine very gentle wife is able to shoot her 3" barreled, 357 Magnum, Ruger SP-101 better than a lot of men I know. (All I did was to take the time to train her right!)