Katy spent Friday night with her on-again beau John Mayer, before stepping out on Saturday to see Bjork in concert with Robert Pattinson. Perry, 28, and Mayer, 35, had dinner at Chateau Marmont in West Hollywood with a group of friends. Although there was no PDA between the two publicly, onlookers tell omg! the group was having a fun time together sitting on the patio. The possibly reconciled couple has been spending "a lot of time together" over the past few weeks ever since Mayer attended Perry's Memorial Day party. Sources tell us the duo, who split for the second time in March, are "keeping things light and having fun" together and are "seeing where things go." However, on Saturday night Perry stepped out with her newly single pal Pattinson. The duo arrived together, but they left through different exits and did their best to avoid being photographed together inside the venue. The British actor, 27, was dressed casually in a backwards baseball cap, white tee, and dark jacket and happily posed for a few pictures with fans. Although Perry and Pattinson were together the entire night, an eyewitness tells omg! it "didn't look like a date" and more like "two friends hanging out." These two have been spending a lot of time together since Pattinson and longtime love Kristen Stewart broke up in May. Sources close to the singer have insisted that there is nothing romantic going on between Perry and the "Twilight" actor.