It is impossible to unweave the complex cobweb of a failed marriage and totally understand it, let alone to generalize the occurance for many other couples. But, let's assume the case of a marriage of two typical JW born-ins. As far as JW's go, they grew up without major disfunction, still talk to their parents, etc.
In cases like this, how many of these couples are still together? Since "finding a spiritual mate" was the main goal, many other compatability factors end up being ignored. They marry too young to even know what those issues might be. The WT encourages them to wait until older, but like most kids, they want some sex.
So...from your experiences and observations, how many of these couples are still couples? This is especially of interest if they both are now out. Did leaving the Borg ruin their marriage? Or, did being in the Borg ruin their marriage? Or, did they get lucky and actually find a lasting romance?