Having been an elder for 2 decades - I had lots of opportunities to interact with couples in my congregation as an elder.
I have to say - overall there is a high percentage of bad and mismatched marriages in JW land.
There are many obvious reasons.
One thing that doesn't get talked about is the Negative side of taking divorce off the table for "spiritual couples" who are in what really turns out to be a Bad marriage.
When the threat of divorce is gone - there is LESS reason to compromise and make things work.
I have seen many times in troubled marriages the attitude "well I am not gonna change cuz he or she can't leave me".
Also the stupid thinking that the end is soon - and my wife/husband will be perfect then.
When couples in the real world know the other person may leave if they don't work on the marriage - it can provide a motivation to not just sweep things under the table and not deal with them till there is just disaster - or live a miserable life because god wants you to.
All I can say is that - the divorce rate in my hall was higher than the national average (which by the way is not 50%) - and there really were only a handful of good marriages at best. Even then often they were because the wife accepted herself as the LESSER one to her husband and just did whatever he said.