You should probably come clean with the boss. Tell her you were concerned about looking unprofessional for putting personal plans ahead of your job, and reiterate that you are interested in other professional development opportunities. Finding someone to attend the upcoming trip in your stead might even help smooth things over. It may be embarrassing, but it will be easier than facing the boss if — or when — she overhears about your event and realizes it overlapped with the business trip.
Speaking of embarrassing: If the real issue is that you don't want to have to admit to your boss that you've booked a suite at a Hedonism resort . . . you're on your own.
Karla L. Miller writes an advice column on navigating the modern workplace. Each week she will answer one or two questions from readers.