"Hey are you free tomorrow afternoon?"
"Something came up. Can be free for late afternon I guess. Why?"
"Excellent. Will be there!"
I mean it's not difficult checking someone schedule.
Lots of girls love doing something nice and spontaneous for their guy. It didn't work out this time, she took it well.
"Oh... Yeah, of course. I understand."
"I didn't plan anything big. It was spontaneous."
"You're allowed to have other plans. Haha..."
"So, uh. Happy birthday."
She just got caught off guard:
"(I can't blurt it out now... Crap...)"
"(Maybe it's a sign?)"
"(Maybe it's best to not even tell him...)"
That afterthought was immediately after she was momentarily disappointed. I'm sure it will all be fine.
Imagine if we analysed every conversation in real life the way we do this game!