This subject (subjectivity - based on emotion/feeling, impression and belief or faith) seems to me a discernment of cultures, customs, traditions, rites and good practices (as in etiquette, Savoir Vivre, Decorum, and Social Graces). They are often unspoken rules and used as tools for living together (harmoniously) first and foremost. Multi-culturalism and (now) Social Media are shaking out old rules and generate new rules (for new generations of people) for living together.

I, for one, have a fix on the romantic era (of the 1950s-1960s) and feel lost in the modern times. ;-)