Honestly, it's kind of amazing that people can see a man clearly panicked over his missing sister, with open concern on his face (seriously, it's the most emotion I think we've seen him openly display since the start), and then go "huh, wonder what that was about? Oh well, guess I'll go on my way" after being paid to trick him.
Also, his sisters should be incredibly thankful that whatever they're planning will fail, because if it actually works, and they successfully kill his wife, I don't think he'll be all that happy to be around them anymore.