Would the young man be at fault for leaving the girl he was previously engaged to, especially after his repentance and lack of trust in her, given that his family is not pleased with the annulment of the engagement, and he is keen to protect the girl's reputation and avoid problems with her family?

Praise be to Allah, who has saved you from the sins you were immersed in. Had you died before repenting from them, you would have been exposed to severe torment, for Allah Almighty says: "And whoever does that shall meet the consequences. The punishment will be multiplied for him on the Day of Resurrection, and he will abide therein in disgrace."