Young and Middle Adulthood 33Notably, most of this research exclusively focused on friendships or only compared
friendships and other social relationships. Although this is practical for research pur-
poses and simplifies research designs, we argue that a comprehensive understand-
ing of friendships will only be achieved by considering the interdependencies with
other relationships (e.g., with romantic partners, family members, and coworkers).
The first step in examining interdependencies among social relationships is to
find characteristics that are common to all or most relationships. In the beginning,
we distinguished friendships from spousal and family relationships and from pro-
fessional relationships with, for example, coworkers or service staff. Importantly,
all of these diverse relationships nonetheless can be described by a few common
dimensions, such as emotional closeness and reciprocity of support (Clark & Mills,
1979; Neyer et al., 2011). In general, kin relationships are relatively close and uni-
directional supportive (i.e., low in reciprocity of support), cooperative relationships
are less close but reciprocally supportive, partner relationships are both emotion-
ally close and reciprocally supportive, and friendships are considered as cooperative
relationships that however can be quite close (Neyer et al., 2011). Self- evidently,
more fine- grained relationship categories within these relationship types (i.e., dif-
ferent kin relationships such as with parents or second cousins) further vary in emo-
tional closeness and reciprocity of support (Neyer & Lang, 2003).
Emotional closeness and reciprocity of support are suitable for both describ-
ing a large range of social relationships and examining interdependencies among
friendships and other relationships. For example, how does support provided and
received in friendships depend on how much support is provided to (or received
from) spouses? First, studies show substantial interdependencies among these
social relationships: For example, whether friends are primary attachment figures
relates to whether other attachment figures (spouses, parents) are available or not
(Doherty & Feeney, 2004). Similarly, people feel closer to their friends, the less
close they feel to their family members (and vice versa), and “substituting” miss-
ing emotional closeness predicts higher well- being among young and middle- aged
adults (Wrzus et al., 2011). The understanding of friendships and social relation-
ships in general would benefit greatly from systematically testing interdependencies
among the different relationship types (e.g., kin, partner, cooperative relationships)
and among different specific relationships of a single type (e.g., different friendships
of varying closeness).
Such studies on interdependencies among relationships present several method-
ological challenges. First, multiple relationships per person need to be assessed with
comparable methods. This becomes easily laborious as the average number of rela-
tionships in social networks ranges from 3 to 40 (Wrzus et al., 2013). Second, inter-
dependencies among relationships describe a dynamic process: Characteristics
and changes in one relationship elicit or necessitate subsequent changes in other
relationships. Accordingly, multiple relationships need to be assessed longitu-
dinally. Furthermore, researchers should not rely on self- reported relationship