I am not sure if this is the exact plot but the way many scenarios have aligned, it seems to be the most probable way.
The bet has been revealed. The one of the biggest anchor of the story that started it all for Sameer and Naina.
But the thing that triggered the bet is still hidden from all. Yes, Naina knows the truth but publicly Sameer is still an "Exam Paper Chor.
Naina hid the fact for two reasons. Though it appears selfish, she did it first for her father (to stop him from being dismissed- that time she was not aware of Sameer's innocence) and secondly she did it for her brother (this time she knew Sameer' innocence, theft by his brother). But she HIDES it from all seeing how it will bring bad name to her brother and father.
Both the time Sameer was the sufferer and that made him take the bet.
Viewers assumed this qs Paper issue is now shelved. However, this issue was in waiting to be used at the correct time.
Currently in the show, Sameer is very guilty for what he has done. He is repenting at the same time wants Naina's forgiveness. It's also seems that he has grown very close to Naina' love and care. He wants the things to get to Normal. It is paining him a lot to gradually see Naina not showing any response to his attempts. For Naina, Sameer has done something that cannot be pardoned. (He tried to take revenge against her family and her) Hence, she is doing her best in closing down Sameer and his existence. She is back to me and my family.
In short - NAINA HAS THE MORAL UPPERHAND AT PRESENT AND SAMEER IS AT A MORALLY GUILTY STATE FOR HURTING SOMEONE WHO LOVED HIM TRULY. He wants to get back that love.
In spoiler OLVs, we have seen that Sameer and Arjun got into altercation. Arjun gets to know about the bet and fights with Sameer. Arjun slaps Munna and Sameer gets in to fight with Arjun for that.
During the fight Arjun keeps saying "Badla Lena tha to mujhse leta, Meri galti thi Meri behan ki nahi and inadvertently gives the indication that it was he who stole the paper. Sameer gets to know the truth of paper stealing, however, keeps quiet.
Naina and Swati hear about the fight, comes to the scene and Naina again starts giving lecture and angry words to Sameer on how he is the one always hurting her and her family.
She doesn't know that Sameer knows the truth of paper stealing now.
Even after knowing the fact of paper stealing and how Naina knew about Arjun but hid it, Sameer does not feel anger. (Naina has many times told him that she knows that Sameer did not steal the papers and
Sameer links her statements to the truth he found today.)
Naina's Love has truly changed him and he was no more after revenge. He knew if this truth comes out then Naina (and her family) will be hurt.
Sameer does share this to M & P, who force him to reveal the truth and show everyone the real face of Agarwals. But Naina has changed him. He says it is no one's fault but a series of misunderstandings. In fact, M & P are the ones who started this chain of action by first stealing the key which put Sameer into this scandal. He also adds that he can never hurt Naina anymore.
Sameer makes up his mind to repay for his guilt by keeping this secret to himself.
On the other side, Naina comes to know from Arjun that in his anger he has given the indication to Sameer about the paper theft.
This puts Naina back on the dock. Though still angry on Sameer this doubt of Sameer knowing about her brother's truth makes her feel restless. And also the fact that she hid it.
In the previous week episode, we all saw that Arjun is going to play in a big cricket match. He is under a lot of pressure to perform well. (Due to over expectations from Rakesh).
As it goes, Arjun fails to qualify narrowly for the state team and safari suit goes ballistic on him publicly for not fulfilling his expectations.
However, Sameer intervenes. Sameer surprisingly supports Arjun saying he played well and His father should appreciate that.
Safari suit starts going violent again with Sameer. He starts blaming Sameer for Arjun's failure and how he is a paper thief / how he is a spoilt rich brat / how his upbringing is wrong. Safari suit keeps shouting and vents all his anger at Sameer calling he repeatedly Paper Chor.
M & P had enough and they said " Sameer Chor nahi ... Paper Chor toh aapka ... "
Naina, witnessing all this was tensed and nervous of the truth about paper stealing will be out and after that Rakesh will definitely nearly kill Arjun or worse both Arjun and Rakesh will be dismissed from School. The Agarwal clan will be humiliated. And when she hears M & P about, to tell the truth, she is scared and worried. She is scared that Sameer will tell the truth.
But as expected, Sameer will stop M & P and say to Rakesh " Yes Sir! I am a Paper Chor. You have all the right to hit me. Yes, I am a bad son and disgrace to my parents. I misbehaved with you. Tried to make fun of your daughter in picnic. But then why are you hitting and misbehaving with a good son like Arjun. Do you want to make him like me! Safari suit eventually leaves.
This is the moment of realisation for Naina. The wall of anger and mistrust she had built for Sameer gets weak. She had been very rude because of her anger and mistrust. But Sameer did something which made her question herself. As she approaches Sameer, (visibly shaken from the slaps and insults) she does not know what to say.
But Sameer says, I am sorry Naina what I did with you. Naina is short of words. Sameer says when I made the bet I did not know you. I was angry at you and your father for insults. But after knowing how good you are and how true your feelings are for me, I did not want to complete the bet. However, situations were not in my favor. But that does not make me innocent. I am guilty. So forgive me and please trust I would always protect you and your family. I know your family is your happiness.
As for me, I hope you forgive me. And I also understand that after What I did I will never get the real Naina back who always cared for me.
From today I won't bother you with my sorries and presence. If possible I will move to another school. And Sameer leaves.
This marks the end of Naina's anger. Once she is back to home and thinks over everything, she realizes all that has happened.
The love for Sameer which she had hidden in the anger of his so-called betrayal rises again. This realization makes her restless. After a long time, she again gets into the feeling of fear of losing Sameer. She gets sad thinking all that Sameer has endured because of her and her family (from start until today). She realizes that Sameer's anger was justified.
Though what he did was not right, her family and she herself created the situation by constantly accusing/insulting him.
She also realizes how much Sameer has changed since that day. Now she could clearly see that even in his anger Sameer always protected her. Even in Mount Abu, he took the blame to save her modesty and honor.
All the puzzles just fit together for her now and this realization hit her. It just melts all the anger in her and now fills her with guilt.
The tables turn and now Naina also feels guilty and the love she was suppressing and ashamed of becomes strong once again.
And finally, she makes a call to Sameer after many months of the Mount Abu trip hoping to soothe him and hoping to start from where they had left at Mount Abu.
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I don't say that I have the script.
But seeing the interactions in social media, spoiler videos and precaps, I combined all the instances and came up with this idea.
I assume this is the most probable progression to the story in the current ongoing track.