Ok forgive me if this post seems a little vague, I aint asking for any advice im just wondering.

Do you think people who act in a jealous way, lets say they were very possesive over thier partner. Do you think that person can ever change?? Or do you think if they are that sort of person you will always act jealous/insecure. Or lets put it another way, have you been in a relationship thats ended because of one person being jealous???