Committing oneself to child rearing, that is, one's children, or "the children of tomorrow", in a pedagogical sense, is generally a normative and good commitment, vocational or not. It causes the children to feel trust and security and cements ones vocation as parent or teacher. The only downside of the parental relationship is when parents are badly behaved or when parents are unable to respond appropriately to changes in their grown up child as they become adolescents and adults. When parents and children are both adults, they have years of experience together and each person in the relationship already should have a good idea of the type of person they relate to, and thus stand in the correct relationship to that person.
There are many exceptions to this, such as when someone has raised, either through neglect or inheritance someone with sociopathic tendencies, or when a child is a victim to a parent with sociopathic tendencies, in which case the relationship is more one of guilt to greed, and whatever commitment exists and persists becomes one of suffering.
Another similar commitment is one between adults. This can happen when one attempts to "mate for life". Because it can be difficult for some people to socially adjust to changes, a combination of conditioning and convenience may find them wanting to "mate for life", instead of following the normal social path of investigating and managing the "objects at hand" during relationships.
Of course, one of the objects-at-hand, at least when one is very young and hardly an adolescent, is the parent of the individual in the relationship. This new individual imposed in the relationship may have demands, such as commitment for marriage, as a precondition of permitting the relationship to exist, notwithstanding the recently acquired adult status of their dependent child. Some parents have very high standards in this regard: They will not allow their child to engage in a sexual relationship unless the partner is already self-sufficient and is not a student. Of course this type of inter-generational control is considered old-fashioned by many, in light of multiple methods of birth-control having been available for generations. It nevertheless still exists in many parts of the world and provides a backdrop to this tendency for developing relationships quickly into engagements or even one-sided commitments.
I suppose the upshot of this is that commitments between adults should never be one-sided, they should always be seen as a contract; in other words, the commitment shouldn't exist unless there is an agreement in place to reciprocate. One should not commit to a relationship with another human being when that human being does not comprehend the reason for your commitment and may even for sociopathic reasons accept the one-sidedness as a strategic advantage. One can not merely lead by example.
An antidote to all of these problems, the inappropriate parental control of adult children, which only harms their relationships, the inappropriate "mating for life", could be a symptom of marriage. If there were no marriage, only commitment would stand, and the enablement provided by genuine, free commitment will be the natural order. Perhaps that is something to consider in the year 3000.