Actually she was going to give him a good beating right when he started getting so close to her. But then sometime into the dance, she got lost in it. When Piddi jumped down, stomping on her foot she came out of her trance and was angry at:i) Him daring to come close to her.
ii) Her losing herself in the dance which was something just too girly according.
iii) His overly irritating pagalpanti.
So came the punch.
Somehow she's justified, Piddi genuinely likes the girl, so he should respect the boundaries too. A close dance with a girl who is sometimes irritated by the mere presence of you, it's almost stepping your limits.
Btw Nik just floored me today. He was dancing so amazingly. The look on his face was so charming. And he even lifted Cheshtha!! Wow!!