"They were making out," a witness tells the new Us Weekly (on stands now). "They couldn't keep their hands off each other!"
As the party neared its end, Roberts and Overstreet were just getting started. "They were talking about heading to a hotel pool!" a source says.
Things cooled down the next day at Coachella. "She was leaning into him," a witness tells Us, "but he seemed way more interested in his food."