> the question isn't so much whether he could have tried to help her, as whether it would have done any good.

How about letting her know what was up, thus preventing several months of intense stress and anguish followed by the eventual burn-out?

She deserved to know she was being used as some sleazy douchebag's pawn in his games of office-politics.

The OP claims he tries to be a good person and do what's right. Well, actions speak louder than words.