Breakdown

It is debated whether relationships break down over five separate stages (Duck and Rollie) or five fluid stages (Lee).

According to Duck and Rollie's model, a relationship breaks down over five separate stages: at the Intra-Psychic Stage one person (the Loser; equity theory) has thoughts (Cognitive Approach) of their dissatisfaction but does not tell the other until the Dynamic Stage, when the couple may discuss their issues, perhaps with the help of relationship counselling. If one of more partners continues to be dissatisfied, another threshold will be passed to the Social Stage. Here, partners begin to tell friends and family of their breakup and may begin the division of possessions (e.g. the house) or responsibilities (e.g. childcare). When the relationship is over, in the Grave Dressing Stage, partners often blame each other, presenting themselves in a positive light as an Ego Defence (Psychodynamic Approach). Finally, in the Resurrection Stage the partners learn from their mistakes in anticipation for another relationship.

Conversely, Lee suggests that relationships breakdown over five fluid stages, where aspects of each phase may overlap.  Like Duck, he suggests the process commences with private Dissatisfaction before mutual Negotiation. However, unlike Duck, he suggests we first Expose our Dissatisfaction non-verbally (e.g. withdrawing investments, like sex). He also suggests a period of Attempted Resolution before Termination, which may also occur at any phase.

Convincing evidence to support the role of Duck and Rollie's stage model of the breakdown process comes from Duck who found that participants suggested that they had been willing to make the relationship work and reported being critical of their previous partner at part of their 'breakup stories'. This shows that participants do present themselves in a positive light, as an ego defence (Psychodynamic), as suggested by the model's Grave Dressing Stage.

Further evidence to support the role of Duck and Rollie's stage model for the breakdown of relationships comes from Tashiro and Frazier who found that undergraduate students who had recently broken up showed personal growth in themselves and other potential partners. This gives evidence for the resurrection stage, as they are preparing for future relationships as suggested by Duck and Rollie.

Adding weighting to Lee's fluid phase model of the breakdown process comes from Lee who found that couple were more likely to miss phases in the breakdown process if they are in less intimate of committed relationships. The shows that we can terminate a relationship at any phase as suggested by Lee. 

A strength of both theories is that they are parsimonious, because they are justifiably simplistic in their explanation of the breakdown of romantic relationships. For example, both suggest that the first stage of any relationship breakdown is cognitive, in which one person considers their costs before informing their partner. As this is supported by research for Social Exchange Theory it is likely that relationships do breakdown in this way.

However, a limitation of Lee's study is that it is simplistic, this is because if ignores other important influences within the breakdown of a relationship. For example Duck's stage model explains the last stages of a relationship breakdown (Grave Dressing and Resurrection) because it describes the process after the couple have split, unlike Lee's model (which purely states the relationship has terminated).

On the other hand, a limitation of Duck's model is also that it is simplistic, this is because it ignores other important influences. Lee's model is more positive as it suggests that couples can try and re-establish equity in the attempted resolution phase. Conversely Duck and Rollie's model is more negatively phased without giving partners the opportunity to solve difficulties.

Both theories of the breakdown of romantic relationships can be criticised for being beta biased, which is when a theory unfairly minimises differences between men and women. This is because both theories suggest that we breakdown relationships in the same way, whether we are a man or woman. However, Kassin found sex differences in the breakdown process (women are more likely than men to want t remain friends, where men will break down due to a lack of sex), which may suggest slightly different breakdown processes for men and women. 

Finally, a limitation of the research used to support the theories of a relationship breakdown is that it has low external validity, due to low population validity, which is the extent to which the research can be generalised to wider populations. This is because the models are based of research using a limited number of unmarried, heterosexual partners and it is difficult to generalise beyond these samples.

Due to their strengths, it may be necessary to use a combination of both theories to full explain the breakdown of romantic relationships, taking Lee's fluid phase approach and adding Duck and Rollie's explanation of what happens after the relationship.