She may perceive your manager as a threat to her.
If she is in the biz with you, and if you are a sole prop, depending on the state - she may be an equal partner (like it or not).
My wife is in the biz with me full time. I find that her "instincts" about people are quite good. While I don't listen to her all the time, I do value her input. Sometimes they see things we won't (or can't). However, sometimes she irritates the living bejesis out of me too.
Still love her, though.
I'm not defending your wife - far from it.... just adding some input.