The two were introduced by Joe's ex-girlfriend Mandy VanDuyne and spoke frequently online before actually meeting at the end of 2006, Amelia was supposedly the inspiration of Jonas Brother's song "Australia"; their relationship reportedly lasted around eight months before ending around Joe's birthday in 2007.
It was definitely an amicable breakup since Amelia and Joe continued to be close friends afterwards, fans spotted her at a few shows on the Burnin' Up Tour in 2008.
In 2009, Joe and Amelia seemed to become particularly close again, she was at a lot of the summer tour dates and even came out to New Orleans to go to Joe's birthday party. However, Amelia had an absolute breakdown over Twitter in December 2009, when Joe hosted a big Christmas party, apparently asked her to come out from Australia, and then forgot to invite her again once she was in LA.
Joe and Amelia don’t seem to have interacted much since the incident, but he did follow her new Twitter in 2011 and she tweeted that she bought the Jonas Brothers single Pom Poms in 2013, so it’s nice to see they eventually reconciled after that Great Christmas Party Divide of '09.