Selena Gomez and Justin Bieber have broken up once again, but this time, the 21-year-old singer-actress is determined to finally end the relationship. 

Previous reports state that Gomez and Bieber had recurring fights over alleged cheating, but a Hollywood source revealed that there is more to it.

Gomez has been left suspicious of Bieber's behavior over recent months and according to some rumors she has reason to no longer trust him. 

A HollywoodLife.com source detailed, "She saw stuff on his phone that proved he was lying to her and he's been hooking-up with other girls the whole time, there was no way he could talk his way out of it. They had another huge fight and she says that she'll never go back."

Gomez recently undertook an "Instagram cleanse" where she deleted former friends Taylor Swift, and siblings Kylie and Kendall Jenner.  It turns out that Gomez was concerned about them being huge influences on her hard partying habits and wanted to distance them for the moment as she recovered.

Kendall Jenner was also the target of other recent rumors, with some saying she was sending Bieber text messages and that it was these actions that prompted a rift between her and Gomez. 

Another potential issue was Bieber's uncontrolled temper.

"He was begging for her back at first but then as usual he got angry and defensive. They're not talking anymore. She said she was only giving him one more chance and that was it," an insider to HollywoodLife.com said.