If the tear in khanak's eye in the first few secs of the precap are true as observed by Amrita, Shriya, me and some others. This is what I foresee.
When khanak did those rose petals falling on shaan, he was no where amused. Even after the phoonking, he just leaves with irritaion in his eyes. So as khanak tries all her methods he may get irritated may end up bad mouthing her saying - why is she doing all this naatak, tumhe yeh sab mazaak lag raha hai nah. In the garage scenes he always thought that khanak's actions wre to make fun of him. He is pissed thinking she is still happy inspite of the fact that they will separate in few hoursAnd when he's angry neither he nor any of us can guess what all comes frm his mouth - but we can be sure Khanak gets hurt with whatever he says.
As Amrita said in the other thread she may enter the washroom, crying badly - the way she cried in the kitchedn after the nattie engmt. Also sitting/kneeling under the shower while crying with deep hurt is also a common thng ppl do (atleast I do). So Shaan hearing her crying may finally feel bad and come to console her. He may lift her and look into her eyes - as per the first few secs of the precap just look at the expression in shaan's eyes - just b4 they show teary the teary eye of khanak - it was not passion but it looks like he was reading her eyes.
So they end up together in the shower.