Not true at all. It wasn't circulating for a long time in news rooms at all. There were no rumors for months. That's a lie.
There were a lot of stories about Meghan ghosting her friends and falling out with everyone. (So tabloids wanted someone to fall out with Kate also, that's way they work. Pitting people against each other.) Then out of nowhere that rural rivalry story came out and people began speculating why they were falling out. (Which wasn't true evidenced by Kate inviting her and her husband to her birthday. And also that she was standing with Kate's parents/close friends)
Then Nicole Cliffe (who is American and a big fan of Harry and Meghan) made a twitter thread speculating why they were falling out. She came up with that affair story. She said that must be it that's why Harry fell out with him. (In the end she deleted her twitter. Later on her blog she said I was just speculating I know nothing.)
In touch weekly (American tabloid) picked it up and ran a story about the supposed affair and that went viral in twitter.
So that twitter thread and story from In touch weekly) went viral.
So Giles Coren also read it on twitter because that twitter thread / In Touch Story went viral. So he made a tweet about it (that's just Giles Coren being him, he tweeted many abhorrent things).
And American media then went viral with it because a respected journalist (LOL) from UK tweeted about it.
Of course later he retracted it and deleted tweet. He also wrote an article in the Times end of last year to say it was fake news and he was joking but that American media are still quoting him and that he feels sorry for William.)
This also confirmed that there is no super injunction otherwise he couldn't write an article in the Times. If there was one no journalist could write or hint about it. So that's another story debunked.
Then journalist / paper in UK wanted to write a story and contacted palace. And that's when lawyers from William stepped in. His lawyers sent a letter to that newspaper and other media. In that letter his lawyers said that it was FALSE and HIGHLY DAMAGING. And they would sue. So not one UK tabloid touched it.
UK Media is most vicious media there is. If they had two sources to confirm or had any proof they would have printed it. No doubt about that. They did with every royal scandal in the past.