If its temporary, plan a great holiday for the summer, and get her to carry round postcards and images of the beaches.
If its permenant, leave the job.
In addition to what ART has said really, I've noticed the trend of "The more capable and accommodating (i.e. doing things way above and beyond your job description) you are, the more shit you'll get dumped on you" getting even stronger. Not sure why, I think its because there are more incompetent people around, who have gone through an education system that responds to moaning and disruption, sidelinging the diligent and conscientious. Nicholas Nassim Taleb has a good approach for this – be nice and friendly and open most of the time, but once in a while 'walk the walk' – do something unexpected and harsh, like destroy someone for no discernable reason in a meeting (preferably an a**shole).