Brittany, who's an admitted Swiftee, joined us Monday on "TMZ Live" for a closer look at the timing of Taylor's breakup going public -- and, as an expert on Taylor's marketing brilliance, she suspects the singer is, in a way, manipulating the media.

For starters, Brittany says Taylor has always been meticulous about managing news cycles ... so it's quite interesting for the split to "leak" to the public smack in the middle of a 13-day break in her Eras Tour.

Brittany says the timing of it all suggests Taylor wanted the story to break so she would be back in the news during that break in the action ... shifting attention and momentum back to her tour when she would, otherwise, be off the radar.

As we reported ... Taylor's last-minute song change in her setlist is also getting picked apart. She removed "Invisible String," a song about soulmates, and inserted "The 1," a track reminiscing on a former relationship.

The timing of Taylor and Joe's breakup is unclear, and Brittany speculates the split might have happened weeks or even months ago ... and the song swap could have been intended as a hint to fans.

Don't get it twisted, Brittany isn't suggesting Taylor would time a breakup for a marketing opportunity ... but she thinks there's at least a decent chance she was waiting to see if news of the split came out during the tour.