Why was that a big shock at the end? Remember when she finally agreed to marry him, she is still under the impression that he cheated on her and even had her murdered in the previous timeline. She agreed to marry him while internally under the impression that he'd eventually cheat on her and throw her away. The moment he switched to work under the princess, while hiding that information from her, she should have immediately concluded the cheating had started.

I'm curious what her next steps will be though. Continue to stick her head in the sand like she has been ever since she agreed to marry the man she believes will inevitably cheat on and eventually murder her? Confront him? Run away? Present divorce papers? I'm hoping for that last one, but expecting the first one.