While with Arjun, she appears more like an irritating sibling, or a friend rather than a love interest, at least from my pov.
On top of that a gut feeling tells me Arjun is going to suffer some tragedy soon. And that is sure going to be painful.
So Shan, if he remains busy with Noori, Arjun will have one less problem...wait no, he will have two less problems to deal with and the Shan-Noori scenes will be entertaining to the viewers too.