It's just a very frustrating situation.
Frustrating as it was - as he was - it would do no good to question him further.
It was frustrating to work with someone who didn't try, but if it had not been for him trying to rescue her, she might be the one on that bed – or in the morgue.
If he found her so frustrating, why did he want to go out with her again?
It was frustrating, but the only thing she was accomplishing with this interrogation was making their conversation stiff and formal.