You can not change the people around you. But you can change the people that you choose to be around.
You can't always change the people around you, it has been hard enough to change yourself right? All that you really have control over when you are dealing with others is if you really want to deal with them, and work things out, or if you do not.
There are many relationships that can be fixed with just a little work, but if both parties aren't willing to change and compromise, then there is more than likely, no god reason to attempt these changes, and it will probably just be best for both parties to move on.
Some people are just toxic to your life, and it doesn't mean that they are bad people. It just means that your lives are going in two different directions, and that the only way you both can live your best is to split apart so that you both may have room to grow.