In terms of Jake's injury and his conception of manhood, is Jake successful as a self-healer in The Sun Also Rises?
This question requires quite a bit of interpretation and therefore opinion and so must be argued (as opposed to proven).
The briefest response to the question is “no”, Jake is not a successful self-healer. In healing himself, Jake fails utterly. The best we can say for Jake, in terms of recovering his manhood and mending his wounds, is that Jake returns to the same emotional place he occupied at the opening of the novel.
Regarding Brett, Jake began with a wistful and narrow hope that the two could form a real romantic relationship. The hope was wistful and narrow because it was based only on the most precious and fragile thing in this book – love.
Love is not enough for Brett and it is not enough for Jake. The wounds to his dignity and to his person, for Jake, are only the outward signs of the wounds to his emotional being, if we can put it that way, which are inflicted by Brett and Brett alone.
In the end, Jake can go back to being wistful and can give up on the majority of his small hope, but he can’t be said to be potent or dignified or healed.