DEAR MISS MANNERS: We were meeting up with longtime friends. Discussing types of vacations, I expressed some concerns about cruises — specifically the effect they have on the environment in places with fragile ecosystems. That’s when my friend told us she and her husband were going on a cruise to Antarctica. Yikes! I fear I have offended her with a holier-than-thou attitude. How do I fix this? What should I have done? GENTLE READER: How refreshing that you would not rather make it worse, in the name of Truth or Principles or Just Generally Making People Feel Bad. The only way to handle this, …