Gomez had the audience captivated as she sang, "Hand over heart, I'm praying ... That I'm gonna make it out alive" and "The bed's getting cold and you're not here ... The future that we hold is so unclear."
One person, in particular, was moved to tears -- Swift.
During the performance, Swift was sitting in the front row and looked up at Gomez with a furrowed brow, and her eyes welled up a little bit.
Even Gomez got a little teary eyed. There was a lot of talk on social media after the performance that the song and emotional show may have been focused on Gomez's ex, Justin Bieber.