I think you’re conflating two elements in the same relationship: the love the mother has for her child and the responsibility. The responsibility has to do with the fact that it is an adult/child relationship. As an adult, we are the ones responsible for the care of our children. But love does not depend on this kind of relationship. It can exist between two adults, or between a child and her teddy bear.
If it exists between two adults, the kind of “slavery” you get (if you want to call it that) is, if anything, the reverse of what you described. Usually, the one who is in love is the one who enslaves him/herself into the service of the loved one. The man, for example, might buy the woman flowers, might go out of his way to take care of her, might respond to her every beck and call. He basically surrenders his selfish will to serve hers. If anything, he allows himself to be owned by her.
I think it’s because of this conflation of love and responsibility that you think it’s the other way around. To be responsible to someone else, particularly to a child, means to carry the burden of having to make sure the child never gets into trouble, or gets hurt, or gets sick, etc. And because he/she is a child, he/she is less capable of, and knows less about how to, take care of him/herself. Thus, fulfilling this responsibility entails telling the child what to do, what not to do, what to eat, when to take a nap, rewards for good behavior, punishment for bad, etc. This is where you get the appearance of “ownership”. It rests on responsibility.
Between two adults, there is no responsibility. Each adult is fully capable of taking care of themselves. Thus, the love expresses itself as self-enslavement, not the enslavement of the other person. But in the case of a parent to a child, the love expresses itself as the enslavement of the child. What’s common in the two cases is the desire to fulfill the needs and happiness of the other. It is assumed in the case of two adults, that each adult is fully capable of deciding for him or herself what he/she needs and wants, and how he/she can go about getting that. Thus, the only thing for the one who loves the other to do is listen to the other’s needs and wants, and how to fulfill them. But in the case of the parent and child, what must be done in order to fulfill the needs and wants of the child is to take the responsibility of caring for the child, which means that as the one who knows best what the child needs and wants, and how to fulfill that, the parent must make the decisions, must be in control over the child.