After a breakup, couple always strictly avoid each other so that the memories of their good time doesn't make them wish to reconcile.
In Malini's case, this hasn't happened. Aditya and Malini are still in touch with each other. She knows the reality and has accepted it but that doesn't mean she can switch off her feelings. Feelings will take time to go, meanwhile they can limit their interactions to divorce talks only. 
I see her return to T house to check on Aditya as a natural reaction of a lover who still has feelings and especially when she is not the one who broke the relationship. Usually in such cases, best friends are saviours. They stop the person from going back to ex but here Malini doesn't have such person in her life. So, I consider it as a moment of weakness of a lover and nothing else.
That's why falling in love is the only easiest thing about love. Maintaining it and breakups are the hard parts of love.