But then one point arises if the bd was for rehearsal only what was the need of wearing khushis suit.
Also sanaya and Barun were shown fighting In the day time. So their is a possibility that they escape in the morning only.
Another possibility is that Khushi does not meet arnav this time . She comes again the nExt night when she is wearing the red suit. Maybe the cv's want to show her in a red suit for their romantic sequence.
Also I don't think arnav will go back home straight away coz he does not want anjali to know.