I've wondered the same thing. There's no doubt a lot of people who aren't a good fit for each other or hadn't yet attained the requisite level of maturity, resources, etc to make things work who felt forced to marry in some capacity, and the fuses of individuals in such relationships will almost certainly be short. It's a setup for failure.

I believe it's particularly bad for couples who got married under 26 or so, because due to the brain finishing up development and accumulating some real world experience, people tend to settle into who they'll be for the rest of their life at around that age and the change can be stark. It's not hard to imagine a couple who were wed at 20 and very much into each other drifting apart in their late 20s after that shift takes place.