When Harry and MJ are on the balcony just before Goblin makes his first attack in Times Square Harry leans in to kiss MJ but she just turns her head away. Why?

HARRY: MJ why didn't you wear the black dress? My father loves black and I wanted you to impress him. MJ: Maybe he'll like me in this dress. You think I'm pretty. HARRY: I think you're beautiful....(leans in to kiss) MJ: (Turns her head...CRASH)

If you watch the film, MJ doesn't seem upset about Harry's request for the black dress or anything.