"David don't hang up the phone!" Katherine yells into her phone.
"What is it now Katherine?" David sounded frustrated.
She wanted to ask him that very question because of which she is trying to ditch the party although it will cause her family big humiliation but she has no better option than to not appear.
Maverick has clearly said to her that he doesn't trust her unless she publically rejects David's proposal. If she does so then he will take her hand right there and he also promised her that but then... Why is she having second thoughts?
She doesn't like David and marriage with him without his feelings involved and solely for the sake of business definitely doesn't impress her.
She can't convince her dad on short notice and she also can't upset Maverick so the only reasonable thing left to do is abort the party.
If David proposes to her then it was sure they'll get married by the end of this month and she doesn't want that.