OK, Bear with me and hear me out.
I am not sure, if I agree with Neel's reasoning of not letting Nisha know about his past with Saloni.
He is starting a new relationship with lies.
When Nahar threw him out, why didn't he go and talk to Saloni's parents.
He is already hiding stuff from her and now, when Saloni is back to her "childhood age", he is the only one who can help her out. What will he tell Nisha now? Will he again give her some Humanity story?
i think, he will try to help Saloni , but then he will again get selfish and try to keep her with himself.Meaning, he will make her remember her life but only to the point where Saloni is unmarried.
That way he can take the relation ship to where it suits him, which means , he will try to keep Nahar out of the picture and hope that maybe Saloni can be his now.
Which will no thappen, but I am very sure, he will again turn negative
Now your view/analysis