Suggested that adult romantic love involves the integration of three of Bowlby's four originally identified behavioural systems: attachment, caregiving and sexuality. That the relative importance of these systems will vary across the life of the relationships. Of these three, they saw the attachment system as central, forming before the others and so influencing their formation.

They also proposed that attachment style could be related to personal style of loving using the formulation of love styles proposed by Lee (1973). They ignored storge and pragma on the grounds that they were not actually styles of loving.  They expected secure attachment would correspond with eros (romantic, passionate) and agape (selfless love), that avoidant attachment would correspond with ludus (game playing love) and anxious/ambivalent attachment with mania (posessive, dependant love). This theory was tested in a study by Levy & Davis (1988).