Add spaces: Herabilitytodevoteherselfwholeheartedlytosomethingoutsideherselfisunusualinonesoyoung,andtheordinaryself-centrednessandsubjectivityofchildhoodseemsomehowlackinginthefaceofherstrangelymatureloyalty.
Her ability to devote herself wholeheartedly to something outside herself is unusual in one so young, and the ordinary self-centredness and subjectivity of childhood seem somehow lacking in the face of her strangely mature loyalty.