Yes, that's right, no one can remarry unless 'adultery' is proven. Not just committed, mind you, proven. This is why I have known some women to hire private investigators on their exes to prove the deed had been done when the men were playing them but they congregation wouldn't acknowledge it.
I've also known of situations like this... when your 'loving jw husband' cries to the congregation that he's so heartbroken that you're leaving him (but neglects to tell them you're abusing her) and he starts dating someone while the divorce is going on, poised to remarry soon as it's final...and so tells his wife that he'd "better be able to remarry in the kingdom hall; or ELSE"...so a terrified young women has to choose to give up her family to get out with her life and let them have their stinking, backward, dark-ages-mentality oppressive publishing company and just get away...*pointing to self*
I am so sorry for what your relative is going through. It's not right, it's not fair, and no woman should have to stay with a man who abuses her or lose her whole family unless she's willing to live and die alone. It's dispicable.
hugs to you, and your relative...
essie