Reading this made me smile! Thank you for the RR!
Not sure how you're racking the slide, but I use an overhand grip in front of the chamber with the SR9c. That allows me to get solid purchase on the slide, without murdering my off hand with the safety when I rack it. This may sound unnecessary, but try having your wife actively press forward with her strong hand while she pulls with her off hand. When my girlfriend was having trouble racking my pistols, I realized that she was letting her strong hand move with the racking motion, rather than using push/pull. She has no problem now.
Currently Own: Beretta PX4 9mm, Glock 23 (Gen 4), Glock 19 (Gen 4) x2