"Personal animosity" refers to strong dislike, resentment, or ill will between individuals. It describes a deep negative feeling or hostility that exists on a personal level between two people. Full definition
The excessive and, frankly, selfish utilization of the court's process should not be permitted to occur; there must not be resignation that this is the foregone course of domestic litigation where there happens to be the coincidental alignment of personal animosity between counsel, the receipt by them of irrational instructions, and the possession by their clients of substantial financial means. (slaw.ca)
There were rumours his decision was based on personal animosity toward the Howard League for Penal Reform, which is behind the project. (politics.co.uk)
But as much as I am convinced things mostly happen in politics based on personal animosities and perceived public slights, grudges can often be short - lived. (nystateofpolitics.com)