Selena Gomez has invited Justin Bieber to her upcoming secret birthday party, sparking rumors the couple may end up getting to a fight at the event over rumors of her being pregnant and entering rehab because of their last break up.

"No one wants [the Biebs] to go. All her friends want him out of the picture and just want her to have a relaxing birthday with no trouble and they think he's going to dominate her attention," an insider told E! Online.

"She doesn't seem to care that he spends time with other women and isn't always honest with her. She's hypnotized. Her friends just want her to enjoy herself for her birthday, but if Justin attends it might complicate matters."

Selena Gomez is rumored to be getting breast implants-this was reported shortly after Justin Bieber posted a photo of himself on Instagram working out.

Is it possible that rumors of the former rehab star being pregnant and Justin Bieber's attempts to get fit again lowered her confidence?

 "Selena is putting a huge amount of pressure on herself to be sexy because she's afraid of losing Justin," a source told Hollywood Life.

"She feels like she needs to be the hottest girl in the world to keep his attention. She's studied every girl that he hooked up with while they were broken up, at least the ones she knows about, and compared herself to them down to every last detail."

Selena Gomez and Justin Bieber were spotted on a double date with his grandparents at a Los Angeles zoo after he posted a photo of the trip on his Instagram account-it sparked rumors on social media the couple may be trying to get pregnant.

Last week it was revealed they are planning on buying a romantic getaway house together, Hollywood Life reports.

"Justin told her that he wants to eventually buy a house together," a source told the site.

"Like a getaway vacation house, maybe in Mexico."

Could the gesture be a gift for all of the rehab and pregnant rumors surrounding the back-together couple?