first of all whole storyline and characterizations are stupid and illogical. just because we got some good actor the show is still watchable.
what Samrat actually did with Nandini? we at first have to know that. dit she really misunderstood his friendship as love? or there is anything more serious like Samrat gave fake promises, made Nandu pregnant and walked away? but even if he dumped her didn't Nandu know he is married with kids? it seemed she knew so she must have thought before going to any extent with him.
but whatever Samrat did with her Sam was no where involved in that then why on Earth she is trying to ruin her life? is not she woman herself? if she herself known to the pain how she want it for anyone else?
or perhaps she is really a psycho.
now coming to Arjun okay I got Nandu had adopted and raised an orphan Arjun and brainwashed him and he is indebted to her but is not he a grown up man now? he can use his brain for plotting himself then why cant he use his brain to think using people unrelated to their pain be it Bonnie, Sam or even Radhika (even Bonzo on that matter) is how much logical?
Moreover what pain he personally got that he keeps on chanting I have phd on Dard, I got cheated all over my life and all? If Nandini would have died we can understand this but she was alive and took care of him all life. Perhaps he was sent to boarding but so? many parents sent kids to boarding do they turn vengeful?
there is no convincing logic of Arjun's vengeance . I could have thought he is psycho but he had shown concern to Radhika as normal human being so why he cant think normally?
we are terribly needed a better script