What happened to Rose Tyler?

Rose got trapped in a parallel universe with her mother but she couldn't go back because the Doctor had to seal the cracks up again. However, in later episodes Rose does actually find a way to come back but not permanently, and so the Doctor has found new companions since (although he never forgot Rose because he loved her).

She eventually ends up with a half-human version of the Doctor who has the luxury of being able to commit to a life with her, something the real Doctor cannot do.