We have proof of the contrary. There is quite a lot of reports about ppl killing their partners (children, family) when abandoned and then committing suicide. I'm not saying that you should not stand your ground, I'm just saying that your are making dangerous assumptions, some ppl can be irrational or just overwhelmed with emotions. With micro-scale MAD 2 ppl die, with a large scale one you just need 1 person go crazy and it's over. TBH I'd never believe that the real reason for avoiding ww3 was MAD.