Process which begins when one party perceives that other has frustrated, or is about to frustrate, some concern of his, is known as conflict.
A conflict is clash of interest/opinion/ideas.
It is a major disagreement or argument about something. When two or more people are at odds, there is a great deal of conflict between the two of them.
Conflict can lead to a variety of serious incidents, including verbal abuse, aggression, and so on.