Katy Perry, John Mayer "So Affectionate" at Pal's Star-Studded Bash

Katy Perry is once again living a teenage dream with John Mayer.

The recently divorced "Wide Awake" singer, 28, got super flirty with her on-again musician beau, 35, during a recent night out in Hollywood. Hitting up Saint Felix on Nov. 10 to celebrate the birthdays of Hello Giggles blogger Sophia Rossi and New Girl co-creator Liz Meriwether, the tight twosome looked "so affectionate," a source told Us Weekly.John had his hand on Katy's back a lot, and they were kissing and holding hands," the party-goer said, adding that it looked like the pair were "full-on dating."

Also at the bash were fellow A-listers Jon Hamm, Mindy Kaling, Nicole Richie, Shannon Woodward, a...