Mystic just saved me a lot of typing. He nailed it.
My wife is an active shooter. She does not like recoil and I have come to believe that recoil tolerance is like eyesight - it varies a lot from person to person.
If a rifle is over gassed the bolt slams back and is quite noticeable. Not painful, but noticeable. I deliberately download my short range ammo and choose the load that groups the best. It feels much different to shoot than the full power stuff. If you hand load, try dropping the powder charge by 2 and 3 grains.
If you don't handload, install a heavier buffer spring.
I have a NEA 14.5". It is a bit over-gassed compared to some others, but not as much as the Norc.
Noise (muzzle blast) is a big issue. If she is standing behind you, your 223 will sound like a cannon to her. The solution is ear plugs plus ear muffs. I wear this combo in CQB because the muzzle blast from some short barreled braked guns is painful without both.
I installed a S&K liner comp on my 10.5" gun (about $50). It really reduces the muzzle blast.
I suggest that when you start her off the first time, talk about sight picture and squeeze, to get her thinking less about noise and recoil. By the second shot she will realize it is more like a 22 than a cannon.