Justin Bieber & Selena Gomez -- Disastrous Dinner Date

Justin Bieber and Selena Gomez got in an epic argument during dinner Friday and let's just say ... they didn't even make it to the appetizer.

A source inside the San Fernando Valley Japanese restaurant tells TMZ ... the "couple" had an argument while inside the restaurant and Selena left less than 10 minutes into the meal. Justin quickly followed with his head bowed.

According to a photog on scene ... Selena drove home with Justin trailing a few minutes behind. When Justin got to her place ... she denied him entrance at the gate and Bieber drove off.