Sometimes we get so caught up in our own emotions, thoughts and ego that we overlook the fact that the other person in front of us has feelings of their own. We allow our own pain and frustration cloud our vision of what is really going on. We all suffer from loneliness, self-doubt and emotional pain in life. No one has a monopoly on such things and we should try to be more understanding and compassionate towards others, because they too suffer as we do in life.
Forgiveness and empathy are keys to a happy relationship, the understanding of the fact we all are the same far as what we suffer in life opens up the door to forgiveness. Remember we all are human therefore we shall make mistakes, we all feel similar feelings and experience very similar hardships in life. If you look at it like each one of us are a part of a whole, then you will see that if one piece of the whole is broken the whole suffers. So to be compassionate, forgiving and empathetic towards the other pieces is beneficial to the whole as much as it is to the individual.