Even I agree with Gayu. I think the SamHar marriage must have lasted lasted a year at most. I think Sampada must have gotten pregnant right after their wedding or something to appease Malhar. It makes sense that Malhar growinh up with no family of his own would have wanted his own family with Sampada and that too, early on in their marriage. And Sampada must have agreed to it in order to maintain her goody, goody appearance. Cause Malhar isn't that stupid that he wouldn't have noticed an affair for more than a year. And SamThu are not that patient that they would have waited more than a year.
I mentioned this is a previous post, Malhar has a soft heart and he must have seen Sampada as the ideal wife so he must have tried to be the ideal husband to her, which included thinking he loved her. Relative to the show, it didn't take him a long time to get over her love, it just took him a long time to get over his trust and betrayal issues. And I'm sure as a man he feels really embarrassed that he wasn't able to tell that she faking her love and affection for him during their sexual relationship.
With Kalyani, I think he is over the fact that she's a kid. I think he think she is childish but not a kid. The fact that he isn't romantic with her is because he's scared of her reaction that she may think he's interested in her for the wrong reasons. The issue is that he doesn't know whether she loves him or not, so he doesn't want to get close to her until she says she loves him and means it. And he knows after the SR night that she is willing to get close to him even without loving him, so that in some ways made him even more nervous. She would accept his advances but he doesn't want her to until she also loves him, that's why he stayed away from even after that SR night. I think once Kalyani also confesses her love, their equation will really change. Even before all this pregnancy drama, when he wanted a kiss from her, I realized that now that he is more sure that she too loves him (for real), he is willing to get romantic with her and he actually WANTS to get romantic with her.