I'm a left handed guitar player for almost 4 years now. When I started out learning guitar I tried playing right handed and found it terrible. Left handed felt right for me and it still is.
I disagree with Jon that it's difficult to find lefty instruction. Lessons on this site for example are really easy for us lefties to follow. I have never had any trouble learning chords, tab or following guitar video lessons. My private guitar teacher taught the exact same stuff to a righthanded person and didn't have any difficulties finding my errors. We lefties instantly mirror it when we see a righthanded instructor teach us something. I actually found myself picking things up more quickly and easily.
Just let your wife decide what she thinks would be right for her.
JJ
