According to a new report in Life & Style, Selena has always been jealous and worried about Bieber's friendship with Miley.
"Justin and Miley hooked up a few years ago," an alleged friend of Selena's told Life & Style.
"Then he started dating Selena. It created this whole jealously thing between them. Now Selena doesn't want Justin anywhere near Miley - and they've been fighting about it!"
We told you about Miley and Justin's recent time together in the studio on May 16 and days later she presented him with an award at the Billboard Music Awards. She has also posted stuff weird about him on Twitter lately too.
All of this comes after Miley snagged the top spot on Maxim's "Hot 100" list too, beating Selena who was runner-up too. And this supposed drama between the two celebs isn't new either. There were reports Selena was upset when Justin pranked Miley a few years ago on the TV show Punk'd.
Both of the stars are products of Disney. Maybe their jealousy goes way back?
Do you think Selena is really jealous of Miley and Justin's relationship? As sweet as she seems, we're thinking it's a possibility! How could she not be a little worried?