Rihanna (Courtesy Of Twitter)

Selena dissed Justin at the UNICEF concert on Jan. 19 when she sang Justin Timberlake's "Cry Me A River." (Twitter)

It's revealed that Justin reportedly cheated on Selena Gomez with 22-year-old model (slash nursing student) Milyn Jenson in Dec. 2012! (FameFlynet)

Selena Gomez pulled off quite a public dissing of Justin Bieber when she posted a sexy Twitter pic of herself wearing the hat of his favorite hockey team. She deliberately had her back to the camera with a Stratford Cullitons hat on her head facing the camera. The logo of the team was very visibly facing the camera while she held her hands over her head in the universal sign that she's saying goodbye. (Twitter)

Justin and Selena were spotted sitting front row at the YLA show in LA on Feb. 2 and it appeared they were back together! (FameFlynet)

A new report said Selena was getting hot and heavy with co-star rapper Gucci while filming her new movie 'Spring Breakers'. Poor Justin! (FameFlynet)

Justin had a lot of negative things happen to him since his split with Selena: his birthday meltdown, he fought with the paparazzi, he collapsed on stage, and he was photographed smoking what appeared to be marijuana. HollywoodLife.com spoke with experts who tell us it's because of his breakup with Selena! (Fameflynet)

Selena turned heads when she joked about making her ex Justin Bieber "cry" with David Letterman on The Late Show on March 18! (CBS)

Justin was scheduled to fly back to Europe on Mar. 27, but he made a surprise stop at Selena's house before going to the airport! (FameFlynet)

Selena traveled to Oslo, Norway specifically to see her ex-boyfriend. The two reportedly reunited after Justin's concert on April 18. (Twitter)

The adorable pop singers look cozy in this Instagram pic Justin posted on April 26. (Instagram)