A question tag is used at the end of a statement to ask someone to agree with us, or to keep a conversation going, or to ask a genuine, real question:
It was lovely seeing those buildings, wasn't it?
They looked impressive, didn't they?
Since both Helen and Michal went on the date together and saw the same things, these are examples of question tags to ask for someone's agreement or to keep a conversation going.
You're not going to throw up, are you?
Helen really doesn't know if Michal is going to vomit or not, so this is an example of a tag to ask a genuine question.