Harman is not a heartless guy. Being the only son of the family he has to bear all the family responsibilities as well. His life dosen't end with soumya going away from him. But that dosen't mean that he does not love her. It's clear from today's epi how he went to throw that sweater but was unable to do so.
And i don't understand what made you think that harman has started hating soumya. I didn't found anything of the kind in the precap. He is only trying to convince his family that he has moved on in his life, that he has kept preeto's words or maybe he is trying to make them understand that somewhere soumya still resides in his heart and that no one can remove her memories from his heart!
P.s- sorry i went to long to explain my points. I have no intention to hurt you in anyway. This is just my pov. I love reading your post.
If anything went above the line, sorry in advance.