There's a sentence:
She doesn't want to go with us.
How would you use this as a question to specify the cause? Like:
— Would you like to join us?
— No, I will stay at home today. My girlfriend isn't letting me go.
— Why? [question to specify the cause]
From watching TV series I was sure that we can just say:
— Why? She doesn't want to go with us?
But my friends tell me that I should use
— Why? Doesn't she want to go with us?
I feel that saying it like this asks the wrong question, like asking if she wants to go with us, but being uncertain that she will agree (my first language is Russian, and it can be done there). I also can't find anything to support my point of view, hence is my question.