We get this question a lot.
I am left handed, and I play normal right handed.
If you think about what the left and right hand do when playing normal right handed, the left hand has the harder job. The left hand does the fretting, which is harder than the picking the right hand does. So I think they are named backwards.
Anyway, my vote: your wife should learn normal right handed, and avoid the aggravation of trying to find lefty guitars and instruction.
Hope that helps. :)