  Humans are social animals and the interpersonal bonds formed between them are
crucial for their development and well being in a society. These relationships
are usually structured into several layers (Dunbar's layers of friendship)
depending on their significance in an individual's life with closest friends
and family being the most important ones taking major part of their time and
communication effort. However, we have little idea how the initiation and
termination of these relationships occurs across the lifespan. To explore this,
we analyse a national cellphone database to determine how and when changes in
close relationships occur in the two genders. In general, membership of this
inner circle of intimate relationships is extremely stable, at least over a
three-year period. However, around 1-4% of alters change every year, with the
rate of change being higher among 17-21 year olds than older adults. Young
adult females terminate more of their opposite-gender relationships, while
older males are more persistent in trying to maintain relationships in decline.
These results emphasise the variability in relationship dynamics across age and
gender, and remind us that individual differences play an important role in the
structure of social networks. Overall, our study provides a holistic
understanding of the dynamic nature of relationships during the life-course of
humans.
