Also, when either husband or wife wants to get a divorce and they are determined to do so, Is a rav able to say halacha recognized your reason as being invalid therefore, you cannot get divorced?
That’s what a lot of the discussion above is about. The answer is, depending on the circumstances (and I cannot stress that enough), possibly yes. If the get is being contested (in the sense one spouse doesn’t want it) and the other spouse does not have a halachicly justifiable reason for divorce, the Rav is obligated to say no. A spouse is NOT automatically entitled to divorce-on-demand.