i dont think the problem here is why he left...i think the problem here is you've allowed him to effect youre esteem.you are a worthwhile person.he should'nt be needed to validate that.you may have allowed him to use you and that leaves bitterness.to move on with youre life you must realize it was not you making him like he was...its him bottomline...no matter who hes with hes the same person until he decides to change.you,me,god or noone else can do this for him he must do it for hisself.its not a overnite process going threw a breakup but the key is to move on with youre life you have to stop blaming yourself..learn from mistakes and dont take it with you in other relationships.the most important relationship should be the one you have with youself first..if you love yourself you avoid pain inficted by others because you dont allow youself to have those kinds in your life.i hope you look inside first for happiness..hugs..i've been there..now im better!