I just went back and saw the whole thing again and actually what happened was that she started changing in the corner in front of everyone. And he was standing on the other side. She said ab mera ho gaya change toh aap bol rahe ho ki use karle washroom. That's when he started walking towards her. And she said go back and he went. And then he did NOT come back, she came out when she was done. So, it's a lie that he went back knowing that she's changing. She said I'm done but she wasn't. That's not his fault.
And to describe this incident the way she and Vidhi were doing is wrong on their part. It does malign Pratik's character so why shouldn't he speak up.