Couples united like this in marriage think and breathe permanence, and their eternal happiness is based on this idea. For all these reasons they are no longer two but one person - that is, one flesh. To spiritual eyes it is plainly clear that they cannot be torn apart by either one's death.

This new thing should be added to these observations: that these two are not even separated by the death of one, since the spirit of the deceased husband or wife continues to live with the husband or wife who is not yet deceased. And this continues until the other one's death, when they meet again and reunite themselves and love each other more tenderly than before because they are in the spiritual world.  

Emanuel Swedenborg, Love in Marriage, no. 321
first published in 1768