I have a strong feeling that it is Shivin, he is Manasvini's Madhav and Radhika's Krish.
See, though it was Ahan who had hit Gauri's mom as he rode the bike but Gauri met who first...Shivin.
Secondly, it was when her arm brushed against Shivin's, the moment of MadhVini's temple wedding flashed in her mind, moreover they could feel each other's presence and I just love the BGM, totally suiting the situation.
And it is Shivin who is protecting and helping Gauri in the current situation, Shivin is such a good guy, I am so in love with him!!
Plus in the first promo, it was told that Shivin has some secrets, what could those secrets be? Maybe he also has flashes of his past life just like Krish had? Maybe he also paints Radhika/Manasvini just like Krosh had..maybe...
And the cherry on top is the meaning of their names...
Shivin means Shiv, Lord Shiva and we all know what Gauri is for Shiv...
Gauri is the name of Lord Shiv's wife, his better half.
So when Gauri belongs to Shiv and Shiv only, Ahan stands no chance...
So for me Gauri and Shivin belong together. What say?