I think that if they weren’t meant to be seen, they wouldn’t have walked in front of a clearly visible crowd of fans with their arms around each other’s waists, and they definitely wouldn’t have continued walking like a couple once those fans started screaming. And, sorry to say, but I think people who take that as a fluke or as an accidental slip-up are incredibly naive to how these things really work.
From what I can see, they’ve been seeding it for much longer than just that photo in Nashville. People have pointed things out to me in the past few weeks, things that have happened over this year so far, and it goes way further back. Headlines linking their names, them disappearing together for days or weeks at a time, being seen together in small ways over the last several months. It’s kicked up recently, but it’s not new. That’s the point of seeding something — Once things kick up, people are already subconsciously expecting it, because you’ve been giving them small doses of it over time.
(Now, this is about to go a bit beyond the scope of your original question, so I’m putting it under a cut.)