I think if Senior Singhania is released by police when they will be unable to find Arohi n Arjun they had to do that.
Arjun than will drop Arohi safely to her house and may be her family members think not to tell her anything regarding the kidnap n may be Taya jee n Arohi's grandfather will tell Shefali not to tell anything to DJ n Arohi so they may get shock.
If it happens than Arohi's love for Arjun will grow up soon n she will try to be connected with Arjun n so as Arjun.
When she will not be with him he would realize his love for her and their relationship will be grow up.
If this happens that will be the best thing.