According to PWInsider.com, Justin Gabriel decided to quit WWE the Raw before the Royal Rumble PPV. The report notes Gabriel showed up to the arena for Raw that day and found out WWE officials once again had nothing for him, so he decided to leave the building. Gabriel reportedly went site seeing or sky diving, then returned to the Raw arena later in the day to again find out WWE still had nothing planned for him on Raw. At that point, Gabriel decided he no longer wanted to be in WWE.
Gabriel left the arena without informing anyone, and booked his flight back home. In between connecting flights, Gabriel received a phone call from WWE Talent Relations head Mark Carrano, and Carrano asked Gabriel where he was as WWE had plans to feature him in a segment on Raw that night. Gabriel told Carrano he had left the arena and was quitting WWE.
WWE officials were obviously not happy with how Justin Gabriel chose to quit WWE, but they ended up granting him his release from the company shortly before the Royal Rumble PPV.