People are generally nice to people they know. Not always, but generally so. The more a person circulates in the world, the less he or she can know the people who cross his or her path, and the less these other people can be liked. Politeness and mannered interactions are not being discussed here. The subject is liking or not liking.
People are nice or not nice to others, depending on upbringing and temperament. When a person is unkind to someone they don’t know, the person usually feels little or no remorse because the other person has little significance. When a person is unkind to a friend or family member, the feelings will be different unless the two people are already at odds. Unkind behavior has an effect when either person cares for the other and is hurt by the unexpected negative behavior. Unkind behavior wounds and scars relationships and people.
Being friendly, but feeling disdain inside, reaches the other person in an intangible sort of way. Same with pretending to care or pretending to feel warmth when warmth does not exist inside. Expecting ourselves to be nice to everyone who crosses our paths is difficult, but mostly when we let ourselves feel unkindness inside towards the others and towards our own selves.
The more we feel nice feelings towards ourselves, the more we can like others. The less satisfied we are with ourselves, the more people we dislike. Even when we travel the world and meet many people, we can experience empathy, interest, and pleasure with these encounters if we are empathetic, interested in, and pleased with ourselves.
Not liking ourselves leads to not liking others
The work begins within!