Things are getting hotter between lovebirds Katy Perry and John Mayer, but the couple had a chance to cool off at a pool party in the Hollywood hills.

New photos show the couple flirting and enjoying each other poolside as Perry dons a bikin, sips a bottle of beer and Mayer grins as he wraps an arm around her.

A source dished to Star magazine about the couple's hot-and-heavy display: "He was looking down her bikini top, and they were French kissing really passionately."

Onlookers said the pair showed all the signs of a real romance.

"There was major chemistry between them," a spy said. "It was like they were on a honeymoon."

The couple stuck close to one another during the entire party, holding hands throughout and even leaving together.

Perry and Mayer have ramped up their romance in recent weeks as they've been spotted together around Los Angeles. But reports say Perry's friends are concerned her relationship with the noted womanizer - who's dated the likes of Jennifer Aniston and Jessica Simpson - will be bad for the singer, who was just divorced from actor Russell Brand.

"Katy's inner circle was anti-Russell and thought she'd learned her lesson about bad boys," a friend told Radar. "They flipped out after hearing she's crazy about John - they think he's far worse than Russell!"

CLICK HERE to check out the photos of Perry and Mayer's poolside afternoon.