That makes sense to me now. I think I failed to see it like that. But when I rewatched I could see glimpses of him falling for her and understanding her. But it was always in the back of his head that he was doing this for his brother. He couldn’t understand his own feelings because his feelings of anger towards Mishti dominated.
From the beginning he seemed to listen to her (even to agree to consider the rishta right at the beginning), he was also taken aback when his mother flipped the rishta and felt bad for Kuhu, then was comfortable enough to ask her why Mishti wanted courtship - he really listened to her. He says that he can't be her friend because of his hatred for Mishti (Champaner trip I think). After that also you can see where he feels bad for what he's doing to her but it doesn't stop him. There are definitely glimpses where you can see he likes her and maybe that's what kept Kuhu going. It seemed to me more like he was determined not to even think about his feelings for her because of everything else, because if he did, he might not be able to keep doing it. All this was till before the leap.
After the leap and knowing about his birth and stuff, he seems to just want everything to fall in place like before, but after everything he did I think he needs to make more of an effort. Kuhu accepted him as he was, but that was before. I really wish we would see more of an effort from Kunal to address what he did there, but I'm not sure we'll see it since the focus seems to have shifted.