Negative relationships block the progression of a person and their development. Once a person has terminated a negative relationship they can:
1) Grow – after a negative relationship has been terminated a person can appreciate their true being or discover things that they are good at;
2) Become more responsible – getting out of a bad relationship could make a person more in charge of your own emotions and actions;
3) Be happy – after being in a hurtful or unhappy relationship, the person can finally engage in tasks and activities that makes them happy;
4) Be in a healthier and more interesting relationship; and
5) You start loving themselves.
http://www.lifehack.org/324344/this-why-you-should-let-wrong-relationship