Question

The process in which one party perceives that its interests are being opposed or negatively affected by another party, when people disagree, is called:

Answer 1

It's called a conflict.
A conflict does not necessarily because of that one party do a wrongdoing toward another party.
But often time, when more than one parties are motivated to obtain something for the benefit of their own party, they often faced a conflict of interest from another party because they want the very same thing.