Why would a mother's love have room for imperfection that a partner would not? How can a mother's love be all-encompassing?
A mother gives birth to this child either through her heart womb or her body womb and with that the child is born of her imperfections and sadness. They carry her badges of insecurities and imperfections. So, with this are all the mother's hopes, dreams and wishes. A mother wishes for nothing from her child. In pureness her love wishes only to uplift and prepare the child for everything in life.
In good conscious a mother is the first bride of the child- she supports them and teaches them what love should be, how one should love and how one should support and hold others dear.
When a child is born with a handicap it is often viewed by the mother as her own imperfection, her own impurity escaping the womb. She wishes to do all she can to give her child what she perceives to be a normal and average life.
A partner comes and sees all imperfection, you are formed when you meet your partner. They have no need to prop you up although their role should be to strengthen you. You are not born of their imperfection yet chosen to fill the void of it. The mother wants no energy in return, the partner wants an equal energy exchange. It is when this energy imbalance mutates and turns that equilibrium is lost and a relationship ends.
The bonds of parenthood and moreso motherhood cannot be broken. There is no need to reaffirm or to affirm them. They are and will always be, no matter where the child is.
Energetically the cord that travels between child and mother is an interesting energy dynamic. This shall be discourse for another posting.