Relstionship Between Gomez And Bieber Has Been Unstable

They may be going on private helicopter flights, but might the relationship between Justin Bieber and Selena Gomez soon be grounded for good?
According to TMZ insiders, none of whom is named or extensively quoted, Justin and Selena have been unstable for quite some time now. Their status is described as "unstable," by the website, which claims the young superstars have continually split and reconciled over the past few weeks
Having been dating for 18 months, Bieber and Gomez are together at the moment, the source adds, but it's a tenuous situation and their relationship could crumble at any time.
Rumors of a break-up first cropped up in May, following a mysterious Bieber Tweet.
While we have no confirmation in either direction, both halves of the couple have certainly been busy of late. Bieber is flying around the country, performing and promoting his new album, while Gomez recently talked of going on tour some time in the future.
Might such busy schedules simply be too much of a burden for the adorable duo these days? We'll update this pressing story as information comes in.