Yes, This story started with revenge of RK against MB. But Madhu initially support Mukund for a hit and run case and make a big issue eventhough Mukund family agrees for the settlement out of court and sent RK to Jail. The very much same Madhu is now supporting a gangster and talking about true love etc. to him and trying to make a friendship with him. That is the fundamental deviation from social ethics. The gangster may become like this because of circumstances and all but, still he is so. And the great Madhu who started this game with RK for an accident case and now supporting the gangster has not any right to talk about moral or social ethics.
In a hindi movies Hero (Jackie and Meenakshi 1980s film ) they showed the Hero as a dada only, but heroine understand him and love him and after he came from jail she married him also. That is a good story.
But, here initially Madhu loves RK ( Is it true?) because he acted like a good person. She didn't even suspect him even though initially RK told he is taking revenge for 40 years and that excessive hate about her only trigger an attraction towards her. And now she is giving definitions and all for her wrong actions.
And moreover here Sultan is already a gangster, killing his enemies just like that.
I think It is a story between MB and RK who started hating vigorously initially and then slowly attracted.
If Madhu wants to go with Sultan let her go. What is there? That is individual person wish. But she should not talk about others and ethics.
Please take the story like that and we will stop watching and move to Mahabarath of Starplus so that at least we will get to see some good things