You can do it. Check ammo types.
Yeah, you do tend to get lots of flash in a short barreled .357. You can do a couple things to mitigate the problem, though.
Particularly for people who don't shoot a lot - you may want to get your lady a bunch of .38 wadcutters for target practice so she can get used to the piece before you unleash her will full house 357 ammo
Then give her some lighter 357 stuff - like 125 grain HPs - so she knows the difference.
You can get the "designer" premium self defense loads for .357 with short barrels, or even the same for 38 short barrels, that won't flash so much and still provide real protection. Just for fun, if your lady is comfortable with the hot stuff, make sure you let her shoot some 357 hunting ammo near dusk. The foot long blue/orange fireball will surprise her.
By the way - Kludge is right - if you both don't have much experience with handguns, try before you buy, and make sure you try mild target 38 ammo AND the 357 ammo your wife thinks she wants to carry. A titanium 357 snub is more gun than a lot of people think.
Don't turn her sour on handguns by surprising her with more gun than she wants to use.