Raman...as we have always seen him from beginning, doesn't even smile a bit. We know that all this for his bitter past and sorrow. But, he is a human. There had some good moments, but still he forgot to smile each time with family.
But, nowadays, it is seen that due to that lots of tensions and thoughts running in his head, he is shattered. But, at the same time, he is having fun and trying to be happy sometimes...And guys you know, when he smiles, yup right. He smiles when he is fighting with Ishita to irritate her, to make her angry.
Whatever tension he is having, he forgets those for some moments and smile frankly. I am just loving this change in Raman. His tensions can't even take away these smiley moments from him. Ishita is indeed bringing a change in Raman, though gradually.