The two have been BFFs for a number of years now, and we all know Sel is a part of T-Swift's infamous squad. So it wasn't too big of surprise when Selena went all out to let everyone know she appreciates her friend like no other.
"I don't know life without you Taylor. Happy birthday!" Sel captioned a photo she posted of the two when they were younger and then a more recent one of the two. They haven't been spending a lot of time together recently because the two are busy promoting their albums.
Taylor is on the last leg of her 1989 tour while Selena has been traveling the country performing at the Jingle Ball concerts. We're sure they'll be having a reunion sometime soon, though! There's a lot of drama going down in Selena's life right now...you know, with Niall Horan. Who is better for all that than Tay Tay?
Check out Selena's heartfelt message, below.