I think its a deliberate move to keep Mandhaar's identity anonymous and up for assumptions. There hasnt been much reference of him in anyone's conversation except for Pallavi.. No photograph of him in the house with mala n all... So defenitely its because of the way they have chosen to tell the story.
The same goes for Raghav too..his sweeping comments about women being dhokebaaz hints towards a past relationship. But he also values love which makes it even more inrriguing.
Mandhaar to wapas ayega.. which is why they never really elaborated on how he died.. infact the way Pallavi said it looked like he went somewhere and never came back. Did they get his body for cremation.. how he died or disappeared has also been kept under the wraps.
Pallavi and Raghav's past will come to the forefront at specific points in the storyline to add drama..
Achha ho sakta hai banda ..but I wudnt read too much into what shd said.. Pallavi kisi ko bura nahi bolti even people who hurt her..except for Raghav ofcourse but then he is extreme.