(PHOTO) REUTERS/Jason RedmondSinger Ashlee Simpson

Fall Out Boy Bassist is reportedly growing more concerned with his ex-wife Ashlee Simpson's behavior, and a new report claims he is considering getting temporary full custody of their four-year-old son Bronx.

Wentz, 33, and Simpson, 28, divorced in 2011 after three years of marriage and the single mom was awarded sole physical custody of Bronx however the pair still shares joint legal custody. Previous reports claim Wentz grew tired of Simpson's drinking which prompted the divorce and a new report claims her drinking is again out of control.

"Pete is worried that Bronx's well-being could be affected if Ashlee continues to party hard, and he's concerned about her right now," a source told RadarOnline.com.

Simpson is reportedly struggling to deal with her parents' ongoing divorce as well as rumors surrounding her father Joe's sexuality. Wentz, who has since moved on with model Meagan Camper, reached out to Simpson's mother Tina regarding his alleged concerns.

"He spoke with Tina about his concerns and warned that if Ashlee doesn't get a grip and calm down the partying he won't hesitate to get a temporary full custody order in place for Bronx," a source said.

"Tina is heartbroken over the situation. She's been very hands-on with Bronx and loves spending time with her grandson," the source continued. "But, with the situation as it is, if Ashlee doesn't sort herself out soon, Pete believes he will have no option but to go to the courts to get this matter resolved."

It was previously claimed that during her marriage to Wentz Simpson was "reverting to drinking and going out, because she is sick and tired of her life," a source told Us magazine in 2011 adding that the alcohol was "an outlet for her unhappiness, and Pete is getting fed up."