Should a saddle hurt?
I bought a bike last year and after a few rides, I found the saddle very painful. I resisted on riding it, assuming that I'll get used to it, but it never happened, and I was even concerned that I haven't got the right size of a bike. However I got a silicon gel saddle cover and since then the pain stopped. I didn't need cycling shorts or pants either. 

Over time I was thinking that it probably is not the gel cover, but just me getting used to the saddle, till the cover got stolen a couple of months ago, and since then, every time I want to cycle, the pain is back, and I can remain painful even for a few days after an hour of cycling.

As I had read various articles about choosing the right saddles, and based on my own experience riding different city and mountain bikes, the bigger, wider and softer (ladies') saddles work better for me, and possibly for most of the women; (Tip #3 from 7 tips to find the perfect saddle also mentions this), but if she's not willing to spend money on the saddle, you can just get one of those silicon covers to fix the problem, and it's less hassle than wearing the pants/shorts if you're using your bike as a means of transportation in different outfits, rather than just cycling.