Attachment theory
According to the Attachment theory, intimates develop mental representations of the availability of close others that lead to strong cognitive and behavioral patterns of responding to those others. Those who develop a more secure attachment style believe others are available to them and behave accordingly, those who develop an insecure attachment tend to believe others are less available to them and behave accordingly. According to Brennan and Shaver, 1995 and Feeney and Noller, 1990 said that people who develop high levels of attachment have more anxiety and uncertainty. Those types of people cope by seeking reassurance and clinging themselves to another person. These types of insecurity can be related to marital infidelity. With attachment theory, people seek sex to help meet their needs.