Push her hand away.

You push her hand off of your slick member. The absence leaves you wanting more, but , Y'know you need morals and stuff. "Remember when I said one date? Yeah that thing is still happening!" You whisper-yell to her. She seems to disappointed. Her face curls into a frown as she turns away from you. She mumbles a quick "sorry" and leaves to her thoughts.
You try to focus on the movie; failing... Badly. Your mind wanders back to Nicky, your eyes follow soon after. In the shadows you see that she is breathing heavily. The strong scent of sex wafts the air. Only one place you can think of that could be the origin, and you are looking right at it. Her hands fumble down her pants, pulling them down to her mid thigh. Her panties are soaked. Your hard-on, which never quite left needed release.
Nicky eventually looked, all though it was more of a stare, at your "At attention" package. She leans over and whispers, "Are you sure you don't... want to?"