Nope, not at all. Those who meant something retain good memories, those who did not I just say 'sod 'em'. Nothing really phases me much in terms of relationships; I tend to be realistic rather than emotional. That may sound cold, but it wraps me in a protective shield that lessens any potential hurt.
People come and go in your life and that's just the way it is, it's also what makes life interesting and helps to shape you as a person. Embrace those that mean something and cherish the memories they leave you with, the others? Well, they just happened to be around at the time and are best forgotten.
That way of thinking in no way diminishes any horrid experiences that enter your life, it just attempts to rationalise that sometimes rotten things happen to good people but not all people are rotten.