Convenient Animosity

It refers to using hostility, anger, or resentment for personal gain, justification, or manipulation, often disguising one's true intentions or motivations. It also refers to a situation where hostility or ill feelings are maintained or expressed because it's advantageous or beneficial to do so, rather than out of genuine dislike. This kind of animosity is often strategic, used to gain some sort of advantage. It can be a person or a a group of people:
Using past conflicts to justify current behavior
Playing victim to gain sympathy
Manipulating situations for personal benefits
Using anger to control conversations
Only reaching out when needing favors, but ignoring otherwise
Criticizing others choices, but expecting support for their own
etc:)

Convenient Animosity can have a really bad impact on relationships (personal and business), making it difficult to rebuild trust and reliability in them.