As familiarity of each other develops, (often replacing or threatening to replace a fantasy of the other), partners will tend to feel more vulnerable. Although this vulnerability can be the basis of deep intimacy, it is also deeply anxiety provoking.
The pursuer-distancer is the most common defeating pattern seen in unsatisfying relationships. Most commonly one partner will want to talk often about the relationship and will want to spend more time together, and the other partner will want to talk about practical issues and spend more time individually. In every relationship, both pushing communication and closeness forward and slowing them down are necessary functions, but in this pattern the roles become rigid, automatic, and usually polarized.
Frequently the pattern devolves into one partner complaining or accusing, and the other partner defending. The defending partner can rarely see that the nagging partner wants to get closer. A sudden about face by the distancing partner will often switch the pursuer into a distancing pattern, at least briefly. This has led to the conclusion that a pattern exists between two people rather than either person having a personality tendency that is a problem such as "not wanting intimacy" or "being smothering." Distancers don't want infinite space nor are they unaware of closeness, they usually want a set amount, nor more not less.
To change the experience, the task is the same for both parties: to learn to tolerate and enjoy differences.