The one main problem is that everyone sounds sincere and willing to bend with your wishes when they want something. This includes borrowing money. It begins with good intentions and promises of paying back and then can blow up and become an all-consuming stressor.
Once the initial blow of being dumped is over the brain goes into overdrive: If that person phones, I won’t answer. And I’d never accept the apology or excuse. The friendship is over. I’m a wonderful person and I deserve to be treated better.