I see what your saying, Simon, but am not sure I totally agree with it.
My sister, for example. It would kill her to shun me but she'd do it because she really feels that she's doing the hardest thing for her and me, to do what's in my best interests. To her, it would be a sacrifice she's making, and an extremely painful one at that, to do what she believes is in MY best interests.
Can I really find any fault with her???