So to set things straight you are saying that: Wall Street Journal wrote that Peter Morgan was at The Crown premiere with Gillian Anderson, the fandom took that line as confirmation that they are together and then page six wrote that article based on the fandom’s reaction?Do I get it right? But why GA, or PM never cleared the rumors? There are many ways actors can put down rumors without draw more attention.

This is exactly what I’m saying, and I’m sure Gillian or PM will take it down when they feel like doing it. Gillian never indulges rumors, but she finds her way to take them down, even if it’s months after.
But maybe she thinks there’s no rumor, or at least, that it isn’t big enough for her to pay attention to it. It’s actually basically only her hardcore fans who are spinning over and over about it. The press didn’t pick it up. Not even a little. There’s no article anywhere except on Page Six, which is nothing.
To confirm or dismiss a rumor, it has to exist outside of the small circle of your fandom, and it’s absolutely not the case so far.