A relationship is built of strings of moments that our mind has pulled out from where they were stored in memory, moments and memories that come with emotions attached. Memories, spliced together like this in a seamless thread, make a relationship seem continuous and whole. So, after not seeing a childhood friend for years, we can pick up where we left off, as if no time at all had intervened. In this way, too, relationships can be sustained in thought during long absences — parents away from adult children, long-distance lovers, commuting husbands and wives. But the same capacity of the brain to forge this chain of memory can lead to difficulties in a relationship if one member evolves past where the other’s memory left off. So, a child leaving home for college, who left still on the verge of adulthood and returns an independent adult, will encounter a parent’s resistance when the person who steps back into the parent’s memory is not the same as the one who left. It takes a period of adjustment on both sides to set the chain evolving back on a new course.