The model and singer, who split up in Nov. 2016, were spotted as the luxury Villa Zenyara in Palm Springs, which was host to a huge after party on Sunday evening as the festival closed, and was rented out by nightclub 1Oak.
One guest who attended the event said, "Bella and The Weeknd were among an exclusive set of party-goers to be invited to the mansion, which was away from the main site.
"There were no photos of guests allowed and it was a place for them to chill without prying eyes. They are still talking but not together at the moment," Radar's spy noted.
Bella and her sister Gigi Hadid both spent most of the weekend there, and The Weeknd was spotted on Sunday evening as he joined the girls and VIP guests.
"The party was the best over the entire festival, it was very hard to get in and plenty of people were trying to crash.
"At one point there was a medical emergency as someone was laid out next to the lake and medics were rushed in, it was pretty wild!" the source said.
The brunette model, 21, split from The Weeknd, 28, in 2016 after a year and a half of dating. He had bought Bella a puppy for her 19th birthday and they went to a lot of high profile events together, including the Met Gala. But they later went their separate ways.
Bella's pal, Selena Gomez, then romanced The Weeknd. Gomez reportedly dumped him after spending time with ex-boyfriend Justin Bieber, whom she reconciled with (and recently broke up with again earlier this year).
The Weeknd got emotional during his Coachella Music Festival performance about former love Gomez, proving fans who thought two of his songs were about her correct.
The crooner, whose real name is Abel Tesfaye, reportedly had tears running down his face during his headlining set as he sang, "Enjoy your privileged life ’cause I’m not gonna hold you through the night. We said our last goodbyes so let’s just try to end it with a smile."
But now, given that The Weeknd partied with Bella, could he be getting back together with her?
Bella posted pics topless from the Villa site the morning after the party ended at 4 a.m., which showed the breathtaking lake and pool views.
The $350,000-per-weekend home is spread across 40 acres near Coachella, and is often rented out by nightclubs and high profile businesses for private parties.
Sources said Bella actually partied without The Weeknd earlier on in the festival, and only met up with him in private.
"Bella never really lost feeling for Abel and had hope they would eventually get back together," an E! insider previously said. "They are just getting back to a good place. She loves hanging out with Abel and they always have fun together and is very hopeful of their future relationship."
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