Katy Perry, John Mayer Make Out, Selena Gomez Parties With Reese Witherspoon at Met Gala Afterparty: All of the Details, Plus Photos!

Katy Perry and John Mayer
Katy Perry and John Mayer had a steamy night at the Boom Boom Room after the Met Gala. Splash News Online (2)

After the gala, it's all about the afterparty! The biggest stars in Hollywood, fashion, and music conquered the red carpet at the Metropolitan Museum of Art on Monday, May 4, and then let loose (often in different outfits) at a wild Met Gala Afterparty at the Boom Boom Room in New York City's downtown Meatpacking District. Us Weekly was on the scene at the Top of the Standard — site of the infamous Solange, Beyonce, and Jay Z elevator scuffle last year — getting a very close-up look at the star-studded soirée. Click here to see more photos from the Met Gala afterparties!

leo and usher
Usher, Gali Barraza, Leonardo DiCaprio Matteo Prandoni/BFA/SIPA

Celebrating the 2015 Metropolitan Museum of Art's Costume Institute Gala, the swanky affair included appearances by Leonardo DiCaprio, Bradley Cooper, P Diddy, Selena Gomez, Jessica Alba, and Kendall and Kylie Jenner. While he didn't attend the gala, John Mayer turned up at the afterparty, where he met his on-again, off-again girlfriend Katy Perry.

kendall and crew
Harry Brant, Peter Brant Jr., Kendall Jenner, Joan Smalls, Michael B. Jordan Julian Mackler/BFA/SIPA

The two musicians have long remained coy about the status of their ever-changing relationship, but seem to be back on in a big way. Perry, 30, kicked off the night with designer Jeremy Scott, the man behind her playful Moschino Met Gala dress. She did an outfit swap for the party, changing into a blonde wig and ditching her voluminous gown for a jacket and skirt. 

After getting in some quality time with her fashion designer pal, Perry spent much of her evening canoodling with Mayer, 37. The evidently on-again lovebirds stood very close to one another at the Boom Boom Room, leaning in for many passionate kisses and holding hands as they drank champagne and chatted with other famous attendees. 

The affectionate twosome ducked into a back section with pals Allison Williams, Robert Pattinson and his fiancée FKA twigs, and a few others. A longtime Pattinson confidante, Perry bonded with the future Mrs. Pattinson, laughing and hugging the British singer, while Mayer talked shop with the Twilight actor before the men stepped outside together for a smoke. 

rob and fka
Robert Pattinson, Fka Twigs Matteo Prandoni/BFA/SIPA

Later, the group was joined by Oscar winner Eddie Redmayne. The celebrated star said a quick hello to the group, after stunning at the Met Gala with his new wife Hannah Bagshawe on his arm. 

It was a date night as well for fun-loving couple Chrissy Teigen and John Legend, who showed up at the Standard a little after midnight and found a spot in a booth by the dance floor. They weren't alone for long, however, as they were soon joined by Kendall and Kylie Jenner, and publicist pals Jonathan Cheban, and Simon Huck. The Jenner sibs partied with Kylie's rumored boyfriend Tyga and danced on one another to tunes spun by DJ Samantha Ronson. 

Staying out very, very late, Kendall, 19, and Kylie, 17, also gabbed with actor Michael B. Jordan and pal Hailee Steinfeld. One young Hollywood starlet they didn't hobnob with was erstwhile frenemy Selena Gomez.

Jamie Bell, Kate Mara, Michael B. Jordan
Jamie Bell, Kate Mara, Michael B. Jordan Neil Rasmus/BFA/SIPA

Changing into a short black minidress with her fresh flower headpiece still in place, the former child star beamed all night and did tequila shots and lots of dance moves with fellow Disney alum Vanessa Hudgens. Gomez kept the party going with Reese Witherspoon, Kerry Washington, and Alba, speaking to each woman individually and letting loose as a group.

Reese and sofia
Reese Witherspoon, Sofia Vergara, Joe Manganiello Matteo Prandoni/BFA/SIPA

Washington had a long, intimate conversation with Gomez as her husband Nnamdi Asomugha looked on. Gomez and Witherspoon devoted more time to dancing than chatting, breaking it down to Lykke Li's "I Follow Rivers." Jordan popped back up for more tequila shots with Gomez and Hudgens, and spent the better part of an hour dancing with the two ladies, before Dianna Agron joined in. 

selena gomez
Selena Gomez Matteo Prandoni/BFA/SIPA

The Glee hottie was hardly the only blonde beauty at the afterparty, of course, as Jaime King and Diane Kruger also made appearances. Although she's pregnant with her second child, the Hart of Dixie star still managed to shut down the party at the very end, sipping water as she socialized all night with her husband Kyle Newman and four buddies. 

Andy Cohen, Sarah Jessica Parker
Andy Cohen, Sarah Jessica Parker Matteo Prandoni/BFA/SIPA

Kruger also stunned at the Boom Boom Room, turning heads with her longtime love Joshua Jackson. The Dawson's Creek alum canoodled with the actress and model, holding her and rocking back and forth after he had some bro time with a group of guy friends. 

Stepping away from the scene, Jennifer Connelly gossiped with Givenchy designer Riccardo Tisci and three friends on the roof deck. The group critiqued stars' body-baring and daring looks from the Met Gala, strategizing for future fashion ventures. 

Jennifer Connelly
Matteo Prandoni/BFA/SIPA

As the night went on, the party just heated up with additional appearances from Elizabeth Banks, Naomi Campbell, Matt Bomer, Kate Mara, Emily Blunt, Gigi Hadid, Adriana Lima, and even New York City mayor Bill de Blasio

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