I read the following in this rock magizine
Some apologists argue that the exception clause cited above (Matt. 19:9) exemplifies annulments. If “unchastity” refers to illicit relations between the spouses themselves, then divorce is not only acceptable but preferable. But such divorce would not end a marriage, for a true marriage could not have existed in the first place under such circumstances.
I understand the better part of it, but I don’t understand what is meant by “illicit relations between the spouses themselves”.