Black and White thinking, also called All-or-Nothing thinking, is about reducing the complexities in life to simple dichotomies. Things are either terrible or wonderful. We have to be perfect or we’re a failure — there is no middle ground. You place people or situations in “either/or” categories because seeing things in this way makes life simpler to some extent. There is no perceived need to wade into gray areas and make our own determination if something is mostly good, or good enough. But life is full of these shades of gray and ambiguous situations. This style of thinking washes away this complexity and can make interpersonal situations difficult. If a friend lets you down once and you now judge them as a complete flake and unreliable that negatively impacts how you approach and interact with that person and will most likely negatively impact the relationship.