It's a depressing title, I know. But pain is an ever-present part of our lives. Even through the happiest of times, it is the constant strand in a complex array of webs that unites us as humanity together. The types of pain are varied with an infinite amount of levels. Often it is the smallest of things that can consume us and lead us down a path where pain consumes our lives and everything about our existence.
Nonetheless, instead of allowing this shared, underlying pain to unite us, it is rather the most magnified divider of people. In fact, the people who are hurting the most are often the ones to bring others serious pain. As humans, its one of our biggest temptations to subconsciously imagine the world to revolve around ourselves, making our own pain one of the most central aspects of our daily lives, rather than recognizing the hurting that goes on all around us. The small negative things that occur in our lives begin to add up until suddenly we are looking at a miserable existence. This pain can become so great that our simple human minds can't contain it anymore, and it begins to be expressed as harmful verbal or physical lashing out. Internalized pain takes a lot of time to heal, and in the meantime it's extremely difficult to deal with.
However, when we are the victims of these lashing outs, we tend to focus on our own pain and not the origin of where our pain came from. This blindness leads to us ignoring the pain of others and continuing this cycle of pain.
As a little challenge to you, when everything seems to be going wrong and people seem to be hurting you again and again, focus on the pain they might be experiencing. First of all, it's a distraction from your own pain, and third it leads to compassion. And a world of compassion is a world is one of so much less pain... :)