Whether its crime as per the law?
Take: There is no Law in present for the asked que. Society (conservative / customary) are still struggling to give acceptance socially to Live-in in India otherwise it was in existence in India from so many centuries!
Will not it affect the parties in their married life for future in case if the relationship fails due to any reason?
Take: Yes, it depends how the aggrieved at one point of time co-dependence partner now takes life!
Whether any party can seek divorce on this ground that her partner had the history of Live-in relationship with some one prior to his/her marriage?
Take: No, as it is not yet recognised by any provisions of Law.
If any married man/woman is live in relationship with some other, whether the opposite party can seek divorce on this ground?
Take: Que. repeated but with minor twist already answered above J
Take (generic): It is most suitable way of life of nucleus living especially for metro youths but with all due diligence one may enter into it.