This may be a rhetorical question.
I recently got to the house where you start in b/w and the mom says she hasn't seen/ herd from her child in a long time. I have noticed that the mailbox doesn't give a name like Cherin's or Bianca's mailbox does.
Well, while I was playing through the game, it seemed to be implied that your character was out exploring to complete his/her Pokedex. At least, that's the impression I got.
It is impossible to tell
In the memory link feature for bw to connect to its B/W2 counterparts It is revealed that the player character left his/her fashion case from the musical. It is also implied by his moms statement that him/her could have gone on a new journey somewhere else or he may have been one of the trainers you faced taking on a fake alias. but the most likely that has happened is what poke'slash got but I think he may have done sort of a red regiment (going into solitude) or else he has no C-gear signal where he is. Either way we may never know so this is more of a controversial or speculative question than it is a real question.