Have less expectations for those in my life

I think I have been very good about this one, especially when it comes to my kids, husband, and friends. I really wish I could do this with my mother, and father. Its wrong and unfair to them, and it lets me down every time. The only way I can acomplish this at this point in my life is by not being around them or having them in my life, which I am not willing to do. So how do you keep yourself from not expecting something from your parents. Pride, health, or even support that is unconditional?