How might the loss of a beloved pet affect a senior's decision to adopt another one, and what factors should be considered?

Why do people with borderline personality disorder create a narrative where their partner is at fault, and how does this affect their relationships?
Have you ever waited years to get back at someone for a silly incident from your childhood? How did it all play out in the end?
Is it valid for a parent to say they had children because they wanted them to help out when they get old?