Why man repeats the same mistakes

Paulo Coelho quoted, “Waiting is painful. Forgetting is painful. But not knowing which to do is the worse kind of suffering.”
After long waiting, the day has finally arrived. Some accuses, some aspirations and may be a secret desire also accompanied the arrival. We went on closer and closer, though the relation undefined, and ended up in an alien domain from where the route back home was not to be seen.
I am unable to find out why man repeats the same mistakes again and again! Was it a very well designed, well-planned activity? I doubt….for practical people have a reason for doing everything. Often struggle with myself, was it my desire too?
No one knows whenever I ask “why”. He throws back the same question on me and says if I ask you the same question? If I ask you to define our relation and many more questions, he thinks that I too will never have an answer.
He came and went only to leave footprints on my heart…… to make me realize that I am no more the same as I was before his arrival. He made me feel that I have made the same mistake again.
How could I trust someone? What I always think to be love may not necessarily mean to be love but a strong lust…. a never fulfilled desire or may be a challenge. Or it may be just a give and take for what I owe or may be an attempt to shatter my pride.
I feel I am no where-- the defeat left me shattered! I end up in the most awkward predicament. I don’t have a reply to what my people inquires, “Why people repeat the same mistakes again and again?”