Yep, they get married, but in a sense, it´s kinda like when Paul married Irulan. They are married for politics (In the books, the issue is bringed up and Ghani says that she will not commit incest with him) but Ghani´s consort is Farad´n.
I loved the essay, it´s hard to connect with good Dune fans, very glad to read this :)