We're in the exact situation... I've played games my entire life, and my wife can really only play 2D games like Super Mario because she hasn't really learnt how to navigate 3D worlds with the controllers and she's not super good at games that require exact timing.
I've watched a couple of Let's Plays with this game and it looks so fun but I've never picked it up because I thought it would be way too hard for her. It's probably cheap enough now to give it a try and then not worry about it if it doesn't stick for her.
I think this would be a good game for her to get into gaming with. It is a pretty easy game to learn controls. My wife had a real hard time with the 3D controls at first, but is getting more and more used to it.
If you have Xbox or Playstation, this game is free with their subscription services. I don't know what it cost for PC though. If you get this game, I am sure you will both enjoy it.
Oh.. we've got a PS4 that is essentially the media center for the house. I didn't realise it was free. That's awesome! Thanks dude!
Enjoy man. Its a ton of fun.