If everyone and everything in the world died and you were the only one left I'm sure you would commit suicide after about 6 months, I'm sure I would!!
It is a similar with marriage, when you marry you both become one and if your partner dies it is like being cut in half, the loneliness is unbearable for some and the partner will pine away (lose the will to live) and die around 6 months later, some are strong and can start over!
