I think the thought of a three fold cord being a strengthener in marriage was probably to prevent people from linking up with someone from a totally different religion. Think of the stress to be endured at the time the bible was written, if one worshipped Zeus and the other worshipped Jehovah. They weren't terribly compatible and could cause a lot of problems.
The same is true now, the closer a couple is in their fundamental backgrounds and goals, the more compatible they tend to be.
An excellent example is those of us who are no longer buying into the WTBTS dogma, and who have spouses who are still active. It causes tremendous stress.
That people feel trapped in a miserable marriage while active in the Org. is very true. I was married to a total toad years ago, and felt I couldn't get rid of him, because Jehovah wouldn't approve, plus I wouldn't be able to remarry. He finally ended up getting VD and I didn't. I was so happy! Finally I could get rid of the toad and keep my family and friends and not have to worry about getting DF'd for divorcing him.
The thought of being married to an elder is horrifying to me. The wives are often told 'don't be jealous of Jehovah', which I don't think they are, they are just sick of everyone in the cong. coming before them.
CJ