There is no denying that from day one Vihaan was interested in Gunjan not Rachna.
Vihaan currently is trying to get even with both the girls.He did not have to do much against gunjan coz already things are moving in his favor with her. Mayank and her relationship has fallen apart.
He cannot speak to Gunjan right now about his feelings coz she is in her own turmoil & trying to take a stand about her relationship with Mayank
It is very obvious that he is being so pushy with Rachna & leading her on by trying to get cozy with her,appreciating her looks etc
About applying haldi ritual i believe that is it is a belief that you apply to the beloved first or your to be wife/hubby. He applied it to Gunjan first coz she is his choice & Gunjan made him apply it to Rachna coz she thinks it is her fiancee
Did you notice Rachna got worked up when he applied it to Gunjan Coz of the same belief i mentioned above& then he pretended that he must have accidently applied it to Gunjan
That is why everybody thinks that Gunjan & vihaan are going to be a couple in the future
This is not to Offend any MAYAN fans ,just a prediction of how the track may proceed further