WHY ? And How Does It Happen ?

With time, my past life seems to be fading away and almost as if it never existed, but it DID !  How do so many years of your life of pain just seem to pretend as if it never happened? Of course, there are things that I will never forget, and it still brings tears to my face just thinking about the pain that he put me through. And yet to this day, I never knew why....and that's another thing that I don't think that we ever know after the fact, and that is  the reason  WHY !   I see that it happens in all walks of life, from  the average person  on the street all the way to the people who are supposed STARS in Hollywood....and it's no different.  It doesn't seem to matter if you are rich or poor, famous or not so... Is it because we fall in love with someone and they suddenly fall out of love for us because we've done something that our partner is unhappy with? I  DON'T  really think so, and that's because we MUST be happy within ourselves to be happy. We cannot depend on our partner to make us happy. It all starts within yourself. So, perhaps it's something inside of the person who is cheating, that is trying to make themselves happy by doing what they do....without  thinking about the effect that it can have on their partner or family. Does it take a miracle these days to be with someone that's faithful?