In the interesting little book, Law in America, Lawrence M. Friedman tosses out the comment:
My WAG is that this is a holdover from the days of Catholic Spanish rule.
But humans have an infinite capacity for sliding around inconvenient laws and marriages can be no happier in Chile than in any other country. So what do they do in lieu in legal divorce in Chile?
Surely many dopers are aware of it, but I’d like to add that divorce used to be illegal in Ireland until a few years ago. They even had to amend their constitution in a referendum to legalize it.