RE: Deer rifle for small girlfriend
Recommend you & she take a look at the Remington 700 ADL Youth Synthetic model.
This comes with a shortened stock from the factory. I believe the LOP is approx. 12-1/2"
The rifle is relatively inexpensive, and it is still a 700 action. It can be had in .270 which
would fill your requirement of being a common cartridge, ammo availability, etc., manageable recoil, and is well suited to longer range shooting if needed.
I suspect if she is shooting trap, etc., then she should have no problem with a .270.
Good luck, and good hunting!