Taylor Swift & Travis Kelce Attend Backyard Wedding in Tennessee

Taylor Swift & Travis Kelce's "Love Story" wasn't the main focus of a recent event ... 'cause a different couple was getting married, and they just looked on!

The A-list couple was spotted in Tennessee at a backyard wedding ... definitely drawing eyes off the bride and groom, though we're sure they didn't mind.

Taylor's dressed in an ankle-length blue dress while Travis is decked out in slacks and a button-down shirt ... and, though they're two of the biggest stars in the country, they're chatting with everyone like they're any other couple.

The two are smiling and laughing a lot ... though there's no PDA in the snaps -- so, looks like they're on their best behavior around everyone else.

Photos are spreading like wildfire online ... and, it looks like some of the attendees were totally shocked to see the happy couple there -- writing amazed captions and posting for their followers online.

They were also spotted groovin' along as the bride and groom shared a dance.

Taylor and Travis are spending the week together, it seems ... 'cause they were spotted holding hands in Florida Wednesday night -- and, a wave from Kelce sent the fans looking on as they left the place into a frenzy.

After a few months of dodging cameras, we've seen Taylor and Travis out together a few times over the past couple months ... including in Philadelphia on Mother's Day and grabbing dinner in West Palm Beach a few weeks later.

BTW ... Taylor and Travis haven't said much about tying the knot publicly -- but, they're coming up on two years together, so ya never know. An engagement could be around the corner.