Will a girl be held accountable for shunning her brother for a year during her puberty (at 14 years of age), considering the Hadith: "Whoever shuns his brother is as if he shed his blood"?

A Muslim abandoning his brother for a year is forbidden if there is no legitimate Shar’i justification for it, and doing so is a sin for which repentance is obligatory. If the repentance is sincere (nasuh), Allah will erase the sin thereby and overlook the transgression. Indeed, one who repents from a sin is like one who has no sin.