When getting to know somebody, the first impression guides the way. However, reasonable opinion can only form gradually. In doing so, time is a crucial factor as it determines the desire for further contact.
If things work out well, we like the little nuances and details reflected in the interaction, and strangers grow friends. As such, they become part of the personal life, enrich it, and at some point, they are indispensable. While bonding, we built up memories, sharing the good and the bad.
But life frequently consists of decision making, and its consequence is change. As transient as happiness and sadness feel, as temporary is who we are. In the process of time, friends might take too many different turns that no longer merge.
Though this is a sad realization, the memories will always remain. Finally, the process of grieving slowly guides to the conclusion that this transience also means that new strangers will cross the way.