Though it is not wrong for women to perform samashrayanam and bharanyasam before marriage, it is not in practice with many families.
A woman’s life begins only after marriage, before marriage her place is where she was brought up and her life is with the family she is with after her wedding. As her children are going to live along with her, she has to follow the tradition of her husband’s household. Samashrayanam and bharanyasam is not performed prior as she has to adjust with her husband’s family.