Instagram might be free, but one post can cost a reputation or build a lifelong bond. That’s what we thought when we stumbled on the origin story of one of pop culture’s most surprising best friendships: Blake Lively and Taylor Swift.

Look, friendships in fame aren’t sealed with pinky promises; they’re also forged in Instagram captions, voodoo dolls, and pap strolls. Lively and Swift were the epitome of best-friend goals…until the former’s lawsuit against Justin Baldoni allegedly dragged the Blank Space hitmaker into the legal line of fire.

What started in 2015 as a potentially shady moment blossomed into a decade-long closeness involving music videos, godparent titles, and now… a silence so loud it’s hard to ignore. So what happened? And did it really all start with one Instagram post? Yes. And we’ve got every eyebrow-raising detail for you.

Post that could’ve...