They'll never do that.
I was raised Catholic, and self-sacrifice is a central tenet. One of the prayers I memorized as a child contains the lines: "Let me hate myself and love You (God). Let me love my neighbor as myself for the love of You." Somehow or other they never see the contradiction in this.
A relative has been living with me for the past year or so because he is on a fixed income and can't afford a place of his own. I'll probably have to put up with this until one of us passes away. I'm not happy with this arrangement, but I endure because I don't have the heart to put him out on the street. I no longer identify as Catholic, but some things stick with you regardless.
Suppressed anger turns into depression. Prozac helps. It probably would have helped Mother Theresa, but she was so enamored of suffering I doubt if she would have taken it.