Nothing makes the heart ache more quickly or consistently than conflict with the people you care for and love. Some of us, have learned to ignore the pain of conflict, to pretend it doesn't exist. Others of us, have learned to call it out, confront it, speak our minds. Most of us, however, have learned some combination of silence, suppression, and confrontation.
In a conflict it means that another human being, who we may care about, may not see things the way we do. It may mean that they see the world differently, experience things differently.