Roshni a stranger

Watched the SBAS segment. Ravi mentioned that Sid wants to resolve things. That gave me the sense that Sid in fact has not changed in personality. He probably has tried to make things work out after DD's death but it was Roshni who moved away from everything and everyone. But why is what I am wondering? Meaning if Sid has tried and wants to resolve things then why is Roshni being like a stranger. What can be a reason for her acting harsh towards the one person she could not live without? That is the main thing I am looking forward to finding out...