Taking offense where none is meant or given.
Unusual language semantics may lead to misconstrued understandings.
Circadian Rhythms, affecting individual mood states, causing emotional flares where at other times none would occur. Also factors such as physical maladies caused by fatigue or illness or abuse of drugs, may be a base cause.
Intentional adverse reactions to non-offensive communications as an excuse to act against an individual.
Inflexible belief systems absent of reason and incompatible with any other belief system causes varying degrees of offense, some leading to violence and murder.