The JW take on this topic is one of the most telling of their flaws. It is their approach to the bible as though looking at an elephant from four inches away. Most witnesses I remember took great pride in their individual and collective capacity to quote any amount of scripture snippets on any topic. They felt as though they knew the bible oh so well.
But I don't think I ever knew a JW that could step back and talk in a greater context, such as 'why the Apostle was writing this letter to this particular congregation', or 'what was Pauls' overall opinion of ... ?'
I think the first step to answering your question is to get the context: at least read the whole chapter. If you have time, read surrounding chapters and may be even the book. Somewhere along the way, go to the internet and get some non-witness (and I don't mean anti-witness) bible commentary. It only took me a few minutes to locate a handful of deeply-researched commentary on this specific part of chapter 7.
Okay, on to your question: Yup those witnesses trot this little scripture snippet out to show how a woman should stay with her husband thru whatever hell he puts her thru. As long as he doesn't commit adultery she's stuck. At one time (maybe still), even if he had sex with a goat in their bed, she wouldn't have cause - not exactly adultery, you know.
But more to the point, that scripture has NO bearing on remarriage. That scripture is an admonition to a congregation whosae members had taken up the cause of 'denial of the flesh' so zealously, that it was breaking up marriages. But he was also understanding, if someone did it anyway, or had already done it, that they should stay celibate, and maybe get back together later. They were not to use 'denial of the flesh' as an excuse to get out of the marriage. He was trying to keep marriages together - Paul was even telling them to tone down their religious zeal, stay married.
To use this scripture for the reason you cite is to take the scruipture utterly out of context. It is intellectually weak, and is telling of the JW moral weakness in that they do not feel compelled to understand it themselves.
This scripture has NOTHING to do with justifiable reasons for divorce. It has NOTHING to do with limitation on remarriage.
Let me know what you think,
- Buster