Yep, and people are ridiculously good at hiding things they don't want their loved ones to know. Dennis Rader's wife was so astonished when he was arrested as BTK that she had a nervous breakdown, and his poor daughter has PTSD from the shock.

Diane Schuler's husband still refuses to believe that she was a high-functioning alcoholic despite one of the best forensic pathologists in the world explaining her toxicology report to him.

But the book that convinced me the most of this phenomenon was the book that Sue Klebold wrote. She and her husband did absolutely everything "right" as parents and had no idea what Dylan was planning.

It's sad and kind of scary, but it's difficult to ever be sure we really know everything about another person.