how could she not have any idea??

maybe with all that spell craft, he was able to trick the wife into not realizing what was going on by putting her in a psychic maze as well.

People don't sometimes. She was probably busy with academia while he was busy with architecture. Maybe they let each other get on with their own things.

To be fair real life serial killers sometimes manage to completely fool their families. A bigger stretch for me is him building a giant house across the lake without her knowing.