Lester, I am sorry for your pain. I too have experienced this recently. Although I am not an expert, I strongly believe that your issue (and mine) lies in personal insecurity and self esteem issues. I believe that you may still have this feeling again with a different partner because it’s not really about them at all. Everybody has a past and we all have regrets. Perhaps you should seek counselling to begin to repair yourself. That’s what I’m intending to do. Best of luck.