Always a bridesmaid, never a bride! A red-lipped Taylor Swift served as a lovely bridesmaid in her childhood best friend's wedding on Martha's Vineyard, on Saturday.

It was certainly a softer side of the "LWYMMD" singer -- after ranting about how people have screwed her over in her latest single, it's refreshing to see TSwiz take it down a notch, put on a pretty dress and let someone else take the spotlight!

Swift wore a deep burgundy, floor-length gown; her hair was curled into loose ringlets and she carried a bouquet of fall-colored pinks.

Her BFF Abigail Anderson tied the knot with longtime beau, photographer Matt Lucier. Anderson was the subject of Swift's single "Fifteen" on her 2008 album Fearless. The lyrics refer to Anderson losing her virginity: "You sit in class next to a red-head named Abigail / And soon enough you’re best friends / Laughing at the other girls / Who think they’re so cool,” the former country crooner sings on the track. “We’ll be out of here as soon as we can/ And Abigail gave everything she had to a boy who changed his mind / And we both cried."

Here's Taylor with her pal back at Christmastime ...