My husband is unsullied, but the placement of the cup in front of the QoT for so long tipped him off. "Well, clearly she had SOMETHING to do with it."
Edit to add:
The screenplay for this episode was written by GRRM. He made the character choices this go round.
Except, as Tyrion explained to Varys, he told Shae she was in danger so many times without consequence that she just didn't believe it anymore - like he was crying wolf. And during their fight, Shae accuses Tyrion of letting his sister and his father drive his actions needlessly. Shae wasn't going to leave until Tyrion gave her a reason to reject HIM and not the King's Landing situation.
