Secure attachment is defined as a child that will explore and play with toys in the presence of the mother but shows minor distress when the mother is not present. This observation could also be the result of the temperament of the child determined by genetics and the environment. The caregivers behavior as well as the family circumstances influences attachment. Also a higher well-being is characterized by feeling safe, confident, and willing to take initiative. It is also measured by a greater understanding of others emotions, the number of friends one has, and the lack of anxiety issues. While is possible to suggest that there seems to be a tendency between the type of attachment as a child and the future well-being of an individual, it is not possible to definitively say that there is a cause-and-effect relationship because of the large number of variables that affect both attachment and well-being. In other words it is impossible to say what aspect of attachment is directly causing a certain aspect of well-being to occur.
Or if the attachment is causing the well-being at all! Perhaps they both follow from some higher cause, but one doesn't actually influence the other.
What are some influences that would cause both secure attachment and well-being? What are the similarities between them? That might be a good place to start pinning the relationship down.