There are various adaptations of Duvall's (1971) life cycle model used to explain the concept of family development. The information below outlines six stages of the life cycle model used by Lehmann and Coady (2001) with coinciding explanations; this information is our collective interpretation about how the family stressor of infidelity has the potential to disrupt each stage.


Between Families: This first stage occurs when young adults have left their own family-of-origin, but are not yet involved with a partner to create their own family, therefore referring to this population as unattached young adults. If infidelity has occurred in the young adult's family-of-origin, this stage has the potential to be affected. The young adult may have experienced stress and identity development disruption as a result of infidelity occurring in his/her own family, therefore resulting in a lacking ability to develop strong, trusting relationships. Rosenblatt and Waldfogel (1983) explain that some research suggests that children whose parents suffer from infidelity may be more prone to enter into an extramarital affair. The young adult may not have had a family-of-origin template to learn about how engage in long-term, committed relationships and may have difficulty doing so on their own, as a result in infidelity occurring in their family.

The Joining of Families Through Marriage: This second stage refers to a newly married or joined couple. Lehmann and Coady (2001) point out that there is an "increasing rate of
divorce among couples, especially in the first few years of marriage", which would refer to this second stage of the family life cycle. The authors attribute the high divorce rate during this stage to "family crisis and conflict", which would definitely include, but not be limited to, the occurrence of infidelity (p. 90).

The Family with Young Children: It is noted the majority of divorces occur during this period, known as the “pressure cooker” stage (Carter & McGoldrick, 1989, as cited in Lehmann and Coady, 2001). Lehmann and Coady explain that a couple moves from dyad to triad during this stage, which causes them to form new identities. Also, if an adult has not resolved trauma from their past and have trust issues, which could affect the current family functioning. The family with young children that is currently experiencing infidelity could be negatively impacted as they progress through this stage. This is emphasized from the beginning sentence, which relates the prevalence of divorce in this stage.

The Family with Adolescents: This fourth stage involves some difficulty for many families who are learning how to negotiate with their adolescents as they desire to become more independent. The adolescent stage involves a search for increased self and sexual identity; the occurrence of infidelity during this stage of the family life cycle may result in confusion and/or blurred boundaries for adolescents who look to their parents for direction and guidance regarding how to form appropriate intimate relationships.

Launching Children and moving on: This family life cycle stage may be linked to individual developmental issues. Young adult children may be affected by the occurrence of infidelity in regards to how they maintain their own intimate relationships. Buss (2004) as cited in Shackelford et al. (2004) explain that "older women would be less distressed than would younger women by a partner's infidelity...because older women are less likely to have dependent children than are younger women". The couple in the launching stage may be working to try to relate to one another as a dyad again (instead of former triad, tetrad, etc.)...infidelity would certainly interrupt this process.

The Family in Later Life: The later life family stage occurs when children are gone from the home and the family adjusts to a lifestyle that accommodates their parents' older age, including any health problem that may arise. Parents may experience role reversal with their children as they age, lose independence and need to be taken care of (Lehmann and Coady, 2001). Regarding infidelity during this stage, "an older man's sexual infidelity...may provide an important cue to likely relationship dissolution because it is relatively infrequent" (Shackleford, 2004, p. 294).

Some additional points to consider regarding family health, family systems, the effects of infidelity and the family life cycle:
  • Thorson (2009) discovered the secret keeping was a common tool used in family systems who experience infidelity. A child who resorts to or is encouraged to keep secrets, might feel like he can maintain homeostasis by keeping the secret.
  • Thorson (2009) also found that young adults would often use code words to discuss their parents infidelity, as opposed to referring to it as an "affair" or as "infidelity". How effectively can young adults (or children...or anyone!) emotionally process thoroughly without being able to call the event by it's real name?
  • Families may identify patterns of infidelity "within several generations of their family" (Moultrup, 1990, cited in Hertlein, et al., 2005, p.13)
  • Appropriate boundaries are needed within a family to help the system maintain it's balance (Rosenblatt and Waldfogel, 1983). Does the presence of infidelity mean there are poor boundaries within the family system?
  • Infidelity may exist as a system itself, or a subsystem of a family system.