In spite of being left to his own devices since childhood he has turned out to be remarkably level headed and principled. By nature he is an emotional person who learnt early on to hide his true self behind the bratty image. Maybe that protected him from his step fathers barbs and taunts if he behaved as if he was thick skinned. And of course his shallow mother never understood but Nanu did.
As to what to expect of him, I think Sameer will be forced to come out of his comfort zone because Naina will be shattered and we already know that he doesn't want to see her sad. And here he has given her the biggest blow. So yes, he will be forced to come out of his comfort friends zone. Maybe Nanu and Mand P can help him understand. Because if he doesn't take the next steps this story stops here. I think Naina will not be able to overcome this blow by herself, she is practically an emotional' orphan and quite lonely who satisfies her emotions by building up stories in her mind. Sameer is the first person to whom she has expressed her innermost thoughts. Hence her emotional involvement in this relationship has been 110%. So she needs a push to get over this setback. This will make them both grow up for sure.