Attachment theory is not a general theory of relationships. It is, rather, a theory specific to those relationships most important to our feelings of security—relationships on which, as West and Sheldon-Keller note, our feelings of security depend. For children, these are relationships with parents. For adults, they are, foremost, relationships of emotional partnership, of courtship and cohabitation and marriage: relationships whose formation engages the full energies of participants, whose existence provides each of the participants with a sense of anchoring and augmentation, and whose loss gives rise to grief. They are relationships in which the other person is irreplaceable, relationships, which permit no substitutes.