Buy the Pitch. Now. Seriously.
I’m a ‘MTB girlfriend’. Only got into it because of the boyf and a friend of mine. I always enjoyed it on my previous bikes – a Camber then a Trance – but buying a second hand 2008 Pitch Comp has made me love it. The bike handles well, feels super stable, and copes brilliantly with everything I throw at it, plus I love the Pikes. So far it’s taken me round FOD and Glentress as well as our local trails (Surrey Hills/Swinley) and given me a huge confidence boost. I’m taking it to the Alps in August and I know that it will fill in the massive holes in my skill levels and help me down the tough stuff.
Size wise I’d get her to try a medium if you can, my OH is 6′ and rides a medium, IMO it’s a bike that’s better a little smaller so you can chuck it about a bit.