She loves RK truly. She knew what she is getting into by loving this complicated man. Remember thw 'aag ka dariya' conversation by the lake side? But, with her idealistic view towards life, she thought she can change this man for good. And this is where she went wrong terribly.
And now after seeing his prem game, somewhere she seems to be blaming herself for falling in love with him. Though she never overtly expresses it, her actions convey this to me. Also, today she even went ahead and said that she feels disgusted with herself for loving him ever. So, all in all she is losing belief in her capability to love another human being. And that is why, now she feels the need to shower her love on Aryan, which will help her restore her faith in her ideal principles of love.
As to why she is hanging around his sets, there might be two reasons. She wants to be around RK, so that she can become like him. A person who is evasive, adept at keeping secrets and hiding their hurt. This is what RK is. And this is what Madhu has become gradually. By being around RK, she has managed to bury her hurt under that tough exterior.
What reason Madhu has to not dismiss him? She can't openly display that she still loves him and has her hopes invested in him. RK has not given her any reason to do so.
And if Madhu has moved on, that does not mean she has stopped loving him. It just means that, her life and thoughts do not revolve around RK any more. Her focus is shifting to other aspects of her life, where she can seek solace. But love still continues to hold its place in the heart. Its not operated by a button, to be simply turned OFF once you have moved on.
And lastly, we should not forget that even the most deathless and selfless of love dies out when unrequited. So, if Rishabh Kundra does not buck up soon, I won't be surprised if Madhu's love for him dies out.
That was a long ramble. I hope I made some sense.