It seems to me that even a completely unprejudiced person in Bob's shoes may very well rationally decide that it's not worth the trouble to try to understand Alice's problem. Indeed, I've yet to be convinced that empathy is worth the effort required to achieve it in more than a handful of cases.

When this sort of thing has happened to me, I've said more or less "I'll be here if you decide you want my help with whatever it is," and then turned my back. It seemed to me, then and now, that any other response would have been a complete waste of time and effort.