Ms. Marple,
So after reading everything in this thread, below is my theory based solely on the thread and any links located within it as well as any thoughts I may have formulated on my own. I have no official knowledge nor official contact with sources on this case.
I believe that it is likely we will discover Mr. York has a background of pedophilia. Considering (in it's totality) all of the allegations levied against him, the evidentiary weight connected to those allegations and the psychological typology of pedophiles who engage in incestuous acts, this is not behavior that manifests itself in when someone is in their 50's. I really hesitate to speculate on any potential background he may or may not possess as I have no information to go off of to base any opinion off of.
Whole theory played out from start to finish:
Mr. York went to the DR for whatever purposes (potentially related to Haitian relief efforts as DR and Haiti share an island). While there, he came across AF and realized he had an opportunity here to have his very own child bride. He marries mom as a means of getting AF over to the US.
In less than a year, they are already on the outs and their marriage is falling apart. RF has already formulated her own theory that an inappropriate relationship that is likely sexual in nature exists between AF and Mr. York. She confronts him about this and he tells her she's nuts and doesn't know what she's talking about.
On September 26th, he then goes to the courts and files for custody using mental illness as a guise. This is a tactic often used by men in controlling relationships as a means of discrediting their partners by attempting to convince others that they are suffering from mental illness and thus cannot be taken at their word.
On September 27th, RF in turn realizes what York is trying to do and immediately goes to the courts and levies the accusations against York. Think more of it like a "Game On" type mindset. If he's going to make her look crazy, then she's going to get that information out there as quickly as possible before he's "infected" the ears of the masses. This is where she filed the TRO.
Then on November 14th, 2016, RF vountarily withdrew her TRO. Now i've been sitting here mulling what could have caused her to randomly withdraw her claims and request for the TRO. This is conclusion that I've decided to go with: Not even one week before, Donald Trump has been elected President. Not I refused to turn this into a political debate but it is a well established fact that immigration was a known topic of discussion for the Trump campaign. And what else could be the most ultimate form of control over someone then being able to have them completely ejected from a country! You see, immigrants who marry an American citizen don't get citizenship immediately. It takes a minimum of 3 years. So York uses the threat of having her removed from the country (while keeping the kids because that makes it even more painful for her).
After RF drops the TRO, York knows he's on borrowed time since LE has around gotten word of his "indescretions". He eliminates his problem (which would be RF) and packs up shop. Why move so abruptly? While many people say it's odd, suspicious, etc, there is a very valid reason for doing this. If you had killed someone, would you want to remain around where the cops can watch your every move, where your community can monitor your every action? While it does cast suspicion on the individual, it may actual serve as a means of deflecting some of that suspicion as well as it removes the ability of surveillance.
RF then loses the children to Kentucky CPS and is questioned by LE. Less than one month later, AF goes missing. This was in March of 2018. Three months later, May 2018, AF is found and York is arrested and charged with her kidnapping along with the rape of AF and her younger female sibling.
I surmise that York will not confess to harming RF until he is confronted with direct evidence. I do not see any signs of psychopathy but I also have limited information. I also doubt that the children are aware of what happened to RF. I get the feeling he was too controlling to allow for that loose end to exist. I take him to be a slightly cocky, arrogant guy but not in a manner that would be off putting. Hence why he has supporters. I'd love the opportunity to have some face to face time with him.