Has absence made the heart grow fonder. It sure looked that way ! HollywoodLife.com can exclusively report that the pair looked very happy together and even left together! Do YOU think he wrote his new song, “I’m Sorry” for HER?

Joe Jonas and Ashley Greene broke up months ago, but at a  Friday, Sept 23rd VIP party in Las Vegas they reunited publicly! Insiders tell HollywoodLife.com the pair stayed out together until 3 a.m. Hmm! Did he write his new song, “I’m Sorry” for her as a way to get back into her good graces?

Joe, 22, and Ashley, 24, were both at TAO Nightclub on Sept. 23, and partied with other celebs such as Dancing With The Stars partners Rob Kardashian and Cheryl Burke, a source at the club says. Even though the two broke up in March, they seemed ultra -friendly and like they were both having an extremely good time.

“Joe Jonas and Ashley Greene were both in Las Vegas Friday night for the first I Heart Radio music festival held at the MGM Grand Garden Arena,” an eyewitness tells us.

Ryan Seacrest hosted the two-night extravaganza. On Friday night, Alicia Keys performed along with Jay-Z, Coldplay and The Black Eyed Peas. Following the concert, Joe and Ashley headed over to TAO at the Venetian Hotel.

“After the show, Joe went to TAO nightclub with a group of his friends where he met up with Ashley Greene who was with a bunch of her girlfriends,” our source dishes. “They got there at about 9 p.m. and stayed until 3 a.m. They all looked like they were having a great time. Joe and Ashley spent most of the night together talking and laughing. They were later joined by Rob Kardashian and his Dancing With the Stars‘ partner Cheryl Burke. There was a group of about 25 people.”

Adds a second insider, “They all left together at 3 a.m., Joe and his friends, along with Ashley and her friends.”

Now interestingly Joe Jonas recently admitted that he wrote his new song, ” I’m Sorry”, as an apology to someone whose heart he broke. Could it have been for Ashley, paving the way for them to get back together?

What do you think, HollywoodLifers — should these former flames get back together?

– William Earl, with reporting by Sandra Clark

More Jonas Stories:

1. Nick Jonas & Delta Goodrem Together?
2. Joe Jonas Nearly Runs Into Ashley Greene!
3. Is It Weird For Joe To Hang With Ashley’s BFFs?