Zombie/Horror games are the best to play with a gf, at least my gf loved them. Grab dead island, you can play co-op in it which is totally cool with a controller. She will jump at the scary parts which is so awesome.
I can recommend a couple but it depends on what your girl really likes
Minecraft (she needs to get the hang of it first though but will be addicted)
Mario or the nintendo games, not all are co op though
The sims series