Many promise to stay and many don't. I am so grateful when I am fortunate enough to find a true friend. One who sees all the flaws and shortcomings but focuses on what I DO have to offer and when I AM A GOOD FRIEND.
Hebrews Let your conversation be without covetousness; and be content with such things as ye have: for he hath said, I will never leave thee, nor forsake thee. So that we may boldly say, The Lord is my helper, and I will not fear what man shall do
Usually jealousy stems from feelings of insecurity which developed in early childhood. When we get the message that we are not good enough, or if someone we love is unavailable to us in some way, our sense of who we are can be very wounded, and we feel abandoned as children.
Sometimes the spouse of a narcissist will not defend their child during an abusive attack. The child ends up feeling abandoned. By not protecting the child, it also enables the narcissist continue his/her abuse. Many times the child is told "that's just the way he/she is." The child is expected to understand, and just accept the behavior.